Input: cy8ctmg110_ts - use endian helpers when converting data on wire

Switch to using be16_to_cpup() instead of shifting and combining data by
hand.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210603043726.3793876-5-dmitry.torokhov@gmail.com


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