V4L/DVB (12564): ir-keymaps: Replace most KEY_[A-Z] to the proper definitions

There are several IR's that were using IR to type a letter that it is
known by some random application. Instead, the better is to use
the standard definitions found at:
	http://linuxtv.org/wiki/index.php/Remote_Controllers

And, if needed, submit a patch for the application to understand the
media keys.

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