[media] rc/keymaps: Use KEY_VIDEO for Video Source

Each keyboard map were using a different definition for
the Source/Video Source key.
Behold Columbus were the only one using KEY_PROPS.

As we want to standardize those keys at X11 and at
userspace applications, we need to use just one code
for it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>