media: rc: meson-ir: support MMIO regmaps to access registers

Supports MMIO regmaps to access controller registers in Meson IR driver.

Signed-off-by: Zelong Dong <zelong.dong@amlogic.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>