[SCSI] Mark some core scsi data structures const

patch below marks a few scsi core datastructures as const, so that they end up
in the .rodata section and don't cacheline share with things that get dirtied

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 94e5167f..950b087 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -74,7 +74,7 @@
 #define SCSI_SCAN_TARGET_PRESENT	1
 #define SCSI_SCAN_LUN_PRESENT		2
 
-static char *scsi_null_device_strs = "nullnullnullnull";
+static const char *scsi_null_device_strs = "nullnullnullnull";
 
 #define MAX_SCSI_LUNS	512