[SCSI] pmcraid: redundant check in pmcraid_check_ioctl_buffer()

struct pmcraid_ioctl_header member buffer_length is unsigned, so this
check appears redundant.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Anil Ravindranath <anil_ravindranath@pmc-sierra.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/pmcraid.c

@@ -3751,12 +3751,6 @@ static int pmcraid_check_ioctl_buffer(
 		return -EINVAL;
 	}
 
-	/* buffer length can't be negetive */
-	if (hdr->buffer_length < 0) {
-		pmcraid_err("ioctl: invalid buffer length specified\n");
-		return -EINVAL;
-	}
-
 	/* check for appropriate buffer access */
 	if ((_IOC_DIR(cmd) & _IOC_READ) == _IOC_READ)
 		access = VERIFY_WRITE;