virtio: make VIRTIO a menuconfig to ease disabling it all

No need to get into the submenu to disable all VIRTIO-related
config entries.

This makes it easier to disable all VIRTIO config options
without entering the submenu. It will also enable one
to see that en/dis-abled state from the outside menu.

This is only intended to change menuconfig UI, not change
the config dependencies.
Signed-off-by: Vincent Legoll <vincent.legoll@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/Kconfig

@@ -5,7 +5,11 @@ config VIRTIO
 	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
 	  or CONFIG_S390_GUEST.
 
-menu "Virtio drivers"
+menuconfig VIRTIO_MENU
+	bool "Virtio drivers"
+	default y
+
+if VIRTIO_MENU
 
 config VIRTIO_PCI
 	tristate "PCI driver for virtio devices"
@@ -79,4 +83,4 @@ config VIRTIO_MMIO_CMDLINE_DEVICES
 
 	 If unsure, say 'N'.
 
-endmenu
+endif # VIRTIO_MENU