media: ite-cir: IR receiver stop working after receive overflow

On an Intel NUC6iSYK, no IR is reported after a receive overflow.

When a receiver overflow occurs, this condition is only cleared by
reading the fifo. Make sure we read anything in the fifo.

Fixes: 28c7afb0 ("media: ite-cir: check for receive overflow")
Suggested-by: Bryan Pass <bryan.pass@gmail.com>
Tested-by: Bryan Pass <bryan.pass@gmail.com>
Cc: stable@vger.kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>