Fix toogle whether xenbus driver should be built as module or part of kernel.

The "select" statement in the Kconfig ensures that all other users
of the xenbus will have the same dependency.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

drivers/input/Kconfig

@@ -153,6 +153,7 @@ config XEN_KBDDEV_FRONTEND
 	tristate "Xen virtual keyboard and mouse support"
 	depends on XEN_FBDEV_FRONTEND
 	default y
+	select XEN_XENBUS_FRONTEND
 	help
 	  This driver implements the front-end of the Xen virtual
 	  keyboard and mouse device driver.  It communicates with a back-end

drivers/video/Kconfig

@@ -2070,6 +2070,7 @@ config XEN_FBDEV_FRONTEND
 	select FB_SYS_IMAGEBLIT
 	select FB_SYS_FOPS
 	select FB_DEFERRED_IO
+	select XEN_XENBUS_FRONTEND
 	default y
 	help
 	  This driver implements the front-end of the Xen virtual