fix fail_with usage on Exploit::Remote::MSSQL_SQLI

Same history than #2702

Verification: use exploit/windows/mssql/mssql_payload_sqli

- [x] Before patch: Error message "NameError uninitialized constant Msf::Exploit::Remote::MSSQL_SQLI::Failure"

```
msf > use exploit/windows/mssql/mssql_payload_sqli
msf exploit(mssql_payload_sqli) > set rhost 192.168.172.133
rhost => 192.168.172.133
msf exploit(mssql_payload_sqli) > show options

Module options (exploit/windows/mssql/mssql_payload_sqli):

   Name      Current Setting  Required  Description
   ----      ---------------  --------  -----------
   COOKIE                     no        Cookie value
   DATA                       no        POST data, if necessary, with [SQLi] indicating the injection
   DELIVERY  OLD              yes       Payload delivery method (accepted: PS, CMD, OLD)
   GET_PATH  /                yes       The complete path with [SQLi] indicating the injection
   METHOD    GET              yes       GET or POST
   Proxies                    no        Use a proxy chain
   RHOST     192.168.172.133  yes       The target address
   RPORT     80               yes       The target port
   VHOST                      no        HTTP server virtual host


Exploit target:

   Id  Name
   --  ----
   0   Automatic


msf exploit(mssql_payload_sqli) > run

[*] Started reverse handler on 192.168.172.1:4444 
[*] Warning: This module will leave TFyyxgzt.exe in the SQL Server %TEMP% directory
[*] Writing the debug.com loader to the disk...
[-] Exploit failed: NameError uninitialized constant Msf::Exploit::Remote::MSSQL_SQLI::Failure
```

- [x] After patch: "The SQL injection parameter was not specified...." correct fail_with message


```
msf exploit(mssql_payload) > use exploit/windows/mssql/mssql_payload_sqli 
smsf exploit(mssql_payload_sqli) > show options

Module options (exploit/windows/mssql/mssql_payload_sqli):

   Name      Current Setting  Required  Description
   ----      ---------------  --------  -----------
   COOKIE                     no        Cookie value
   DATA                       no        POST data, if necessary, with [SQLi] indicating the injection
   DELIVERY  OLD              yes       Payload delivery method (accepted: PS, CMD, OLD)
   GET_PATH  /                yes       The complete path with [SQLi] indicating the injection
   METHOD    GET              yes       GET or POST
   Proxies                    no        Use a proxy chain
   RHOST                      yes       The target address
   RPORT     80               yes       The target port
   VHOST                      no        HTTP server virtual host


Exploit target:

   Id  Name
   --  ----
   0   Automatic


msf exploit(mssql_payload_sqli) > set rhost 192.168.172.133
rhost => 192.168.172.133
msf exploit(mssql_payload_sqli) > run

[*] Started reverse handler on 192.168.172.1:4444 
[*] Warning: This module will leave uwNWwypu.exe in the SQL Server %TEMP% directory
[*] Writing the debug.com loader to the disk...
[-] Exploit failed [no-target]: The SQL injection parameter was not specified in the GET path
^Cmsf exploit(mssql_payload_sqli) > 
```