[SCSI] qla2xxx: Add qla82xx_rom_unlock() function.

Encapsulate the unlocking of the ROM lock in a function for better
code readability.

Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Madhuranath Iyengar <Madhu.Iyengar@qlogic.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>