devmem2: mark as deprecated

Busybox has had a devmem applet for a number of years now, so deprecate
the old standalone program.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/devmem2/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_DEVMEM2
 	bool "devmem2"
+	depends on BR2_DEPRECATED
 	help
 	  Simple program to read/write from/to any location in memory.