HID: make boot protocol drivers depend on EMBEDDED

The usbmouse and usbkbd modules are not supposed to be used with regular USB
mice and keyboards. Make them depend on EMBEDDED to prevent them from being
built and loaded on non-EMBEDDED configs.

Signed-off-by: Parag Warudkar <parag.lkml@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>