media: st_rc: Don't stay on an IRQ handler forever

As warned by smatch:
	drivers/media/rc/st_rc.c:110 st_rc_rx_interrupt() warn: this loop depends on readl() succeeding

If something goes wrong at readl(), the logic will stay there
inside an IRQ code forever. This is not the nicest thing to
do :-)

So, add a timeout there, preventing staying inside the IRQ
for more than 10ms.

Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>