Properly handle tristate dependencies on USB/PCI menus

As USB/PCI/MEDIA_SUPPORT dependencies can be tristate, we can't
simply make the bool menu to be dependent on it. Everything below
the menu should also depend on it, otherwise, we risk to allow
building them with 'y', while only 'm' would be supported.

So, add an IF just before everything below, in order to avoid
such risks.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/pci/Kconfig

+if PCI && MEDIA_SUPPORT
+
 menuconfig MEDIA_PCI_SUPPORT
 	bool "Media PCI Adapters"
-	depends on PCI && MEDIA_SUPPORT
 	help
 	  Enable media drivers for PCI/PCIe bus.
 	  If you have such devices, say Y.
@@ -45,3 +46,4 @@ source "drivers/media/pci/ddbridge/Kconfig"
 endif
 
 endif #MEDIA_PCI_SUPPORT
+endif #PCI

drivers/media/usb/Kconfig

-if USB
+if USB && MEDIA_SUPPORT
 
 menuconfig MEDIA_USB_SUPPORT
 	bool "Media USB Adapters"
-	depends on MEDIA_SUPPORT
 	help
 	  Enable media drivers for USB bus.
 	  If you have such devices, say Y.