dbg: add db_incorect_format

Replace duplicated code with db_incorect_format function.

ram usage before patch:
>info ram
ALLOCRAM Current Addr 0x5352bc
ALLOCRAM Remaining Bytes 42308

after patch:
>info ram
ALLOCRAM Current Addr 0x535234
ALLOCRAM Remaining Bytes 42444

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
gdb: remove some chars from db_wdt_cmd

hope this reduce some bits from memory.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
dbg: add new db_unknown_command function to reduce redundand code

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
dbg: use default xxd style for memdmp

result will looks like this:
533f70: 0000 0000 0900 0024 4243 5e00 0201 0000  .......$BC^.....
533f80: 0000 0000 00ff 0000 4801 0000 7431 7062  ........H...t1pb
533f90: d3cf 4c60 de83 9b2a 7431 7062 d3cf f00c  ..L`...*t1pb....

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Merge pull request #20 from olerem/dbg

More debug API work!