dm raid: no longer experimental

The dm raid module (using md) is becoming the preferred way of creating long-lived
mirrors through userspace LVM so remove the EXPERIMENTAL tag.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/Kconfig

@@ -277,8 +277,8 @@ config DM_MIRROR
          needed for live data migration tools such as 'pvmove'.
 
 config DM_RAID
-       tristate "RAID 1/4/5/6 target (EXPERIMENTAL)"
-       depends on BLK_DEV_DM && EXPERIMENTAL
+       tristate "RAID 1/4/5/6 target"
+       depends on BLK_DEV_DM
        select MD_RAID1
        select MD_RAID456
        select BLK_DEV_MD