media: rc: introduce Meson IR TX driver

This patch adds the driver for Amlogic Meson IR transmitter.

Some Amlogic SoCs such as A311D and T950D4 have IR transmitter
(also called blaster) controller onboard. It is capable of sending
IR signals with arbitrary carrier frequency and duty cycle.

The driver supports 2 modulation clock sources:
 - xtal3 clock (xtal divided by 3)
 - 1us clock

Signed-off-by: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>