Input: synaptics - replace NOOP with suitable commentary

Fixes the following W=1 kernel build warning(s):

 drivers/input/mouse/synaptics.c: In function ‘synaptics_process_packet’:
 drivers/input/mouse/synaptics.c:1110:6: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210114152323.2382283-2-lee.jones@linaro.org


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