[SCSI] qla2xxx: fix error handling of qla2x00_mem_alloc()

qla2x00_mem_alloc() returns 1 on success and -ENOMEM on failure.  On the
one hand the caller assumes non-zero is success but on the other hand
the caller also assumes that it returns an error code.

I've fixed it to return zero on success and a negative error code on
failure.  This matches the documentation as well.

[jejb: checkpatch fix]
Fixes: e315cd28 ('[SCSI] qla2xxx: Code changes for qla data structure refactoring')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>