We have table of the HEX characters in the kernel. Replace custom by a
generic one.

Cc: Adaptec OEM Raid Solutions <aacraid@adaptec.com>
Signed-off-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: NEwan D. Milne <emilne@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>