media: rc: do not remove first bit if leader pulse is present

The rc5 protocol does not have a leading pulse or space, but we encode
the first bit using a single leading pulse. For other protocols, the
leading pulse or space does not represent any bit. So, don't remove the
first bit if a leading pulse is present.

Cc: Antti Seppälä <a.seppala@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>