[PATCH 1_4] Merge common get_dev() routines for block devices

Each of the filesystem drivers duplicate the get_dev routine.  This change
merges them into a single function in part.c

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

common/cmd_scsi.c

@@ -194,7 +194,7 @@ void scsi_init(void)
 
 block_dev_desc_t * scsi_get_dev(int dev)
 {
-	return((block_dev_desc_t *)&scsi_dev_desc[dev]);
+	return (dev < CFG_SCSI_MAX_DEVICE) ? &scsi_dev_desc[dev] : NULL;
 }