[media] rc: rc-ir-raw: Add Manchester encoder (phase encoder) helper
Adding a simple Manchester encoder to rc-core.
Manchester coding is used by at least RC-5 and RC-6 protocols and their
variants.
Signed-off-by: Antti Seppälä <a.seppala@gmail.com> Signed-off-by: James Hogan <james@albanarts.com> Signed-off-by: Sean Young <sean@mess.org> Cc: David Härdeman <david@hardeman.nu> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>