add support for sas2ircu for the case where there are no RAID volumes, and add checks for individual disks


sas2ircu just reported CRITICAL any time check_raid.pl was run on a box without any raid volumes.  (we have a number that just have individual disks)

the output from the tool in this case is:

```
LSI Corporation SAS2 IR Configuration Utility.
Version 18.00.00.00 (2013.11.18)
Copyright (c) 2009-2013 LSI Corporation. All rights reserved.

SAS2IRCU: there are no IR volumes on the controller!
SAS2IRCU: Error executing command STATUS.
```

resulting in:
CRITICAL: mdstat:[md0(199.99 MiB raid1):UU, md2(117.60 GiB raid1):UU, md1(31.25 GiB raid1):UU]; megacli:[0 Vols: , 0 Devs: ]; sas2ircu:[ctrl #0: SAS2IRCU Unknown exit]


First step was to handle that case.  Then I realized that we needed to check individual disk status (that's a good thing even if you're checking the volumes!), so added tests for each disk reported by sas2ircu <controller> DISPLAY.



My repro cases on this are limited - I -believe- it should be fine for existing users as long as you don't have failed drives in the enclosure..or more specifically, drive that report anything other than "Ready (RDY)"

Happy to expand it to support other cases if you can provide DISPLAY output for those! :)




example working:

OK: mdstat:[md0(199.99 MiB raid1):UU, md2(117.60 GiB raid1):UU, md1(31.25 GiB raid1):UU]; megacli:[0 Vols: , 0 Devs: ]; sas2ircu:[ctrl #0: 0 Vols: No Volumes: 12 Drives: Ready (RDY)::]

example of disk failure (status anything other than Ready - in this case using a simulated error):

CRITICAL: mdstat:[md0(199.99 MiB raid1):UU, md2(117.60 GiB raid1):UU, md1(31.25 GiB raid1):UU]; megacli:[0 Vols: , 0 Devs: ]; sas2ircu:[ctrl #0: 0 Vols: No Volumes: 12 Drives: FREDFISH: ERROR:Ctrl0:Enc2:Slot9:FREDFISH:]