mvsas: fix build warning, clean prototypes

- Fix build 'make randconfig' build warning spotted by Toralf Foerster:

drivers/scsi/mvsas.c: In function 'mvs_hexdump':
drivers/scsi/mvsas.c:715: error: implicit declaration of function 'isalnum'

- Remove unneeded prototypes (spotted by hch)

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>