dm uevent: no longer experimental

Drop EXPERIMENTAL tag from dm-uevent.

It's not changed for a while and some userspace tools are relying upon it.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/Kconfig

@@ -359,8 +359,8 @@ config DM_DELAY
 	If unsure, say N.
 
 config DM_UEVENT
-	bool "DM uevents (EXPERIMENTAL)"
-	depends on BLK_DEV_DM && EXPERIMENTAL
+	bool "DM uevents"
+	depends on BLK_DEV_DM
 	---help---
 	Generate udev events for DM events.