[media] rc/keymaps: add RC keytable for MyGica X8507

Add RC-5 remote keytable definition for MyGica X8507.

[mchehab@redhat.com: fixed whitespacing - it seems that Alfredo's emailer mangled
 it]
Signed-off-by: Alfredo J. Delaiti <alfredodelaiti@netscape.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>