Input: ili210x - reduce sample period to 15ms

Modern devices may redraw display at 60 Hz, make sure we have one input
sample per one frame. Reduce sample period to 15ms, so we would get up
to 66.6 samples per second, although realistically with all the jitter
and extra scheduling wiggle room, we would end up just above 60 samples
per second. This should be a good compromise between sampling too often
and sampling too seldom.

Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20211108114145.84118-1-marex@denx.de


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>