media: sunxi-cir: allow timeout to be set at runtime

This allows the timeout to be set with the LIRC_SET_REC_TIMEOUT ioctl.

The timeout was hardcoded at just over 20ms, but returned 120ms when
queried with the LIRC_GET_REC_TIMEOUT ioctl.

This also ensures the idle threshold is set correctly with a base clock
other than 8Mhz.

Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>