V4L/DVB: IR: add RC6 keymap for Windows Media Center Ed. remotes

This is the RC6 keymap for the Windows Media Center Edition remotes
that come bundled with MCE/eHome Infrared Remote transceivers. Tested
with 3 different variants of the remote, but its possible there are
still some additional keys missing, but its simple enough to add them
in later...

This patch also adds an IR_TYPE_ALL convenience macro to make life
easier for receivers that support all IR protocols.

v2: fix an erroneous comment that referred to imon devices

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