[SCSI] lpfc: Balance locking

Commit 3163f725 introduced locking in
lpfc_sli_hbqbuf_fill_hbqs, but missed unlocking on one exit.

Reported-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>