Input: synaptics - do not mix logical and bitwise operations

Let's stop using !!x to reduce value of trackstick button expression to 0/1
and use shift instead. This removes the following sparse warning:

  CHECK   drivers/input/mouse/synaptics.c
drivers/input/mouse/synaptics.c:943:79: warning: dubious: !x | y

Also, the bits we are testing are not capabilities, so lets drop "_CAP"
suffix from macro names.

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>