Input: synaptics - demote non-conformant kernel-doc header

Input: synaptics - demote non-conformant kernel-doc header

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

 drivers/input/mouse/synaptics.c:1781: warning: Function parameter or member 'psmouse' not described in 'synaptics_setup_intertouch'
 drivers/input/mouse/synaptics.c:1781: warning: Function parameter or member 'info' not described in 'synaptics_setup_intertouch'
 drivers/input/mouse/synaptics.c:1781: warning: Function parameter or member 'leave_breadcrumbs' not described in 'synaptics_setup_intertouch'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201112110204.2083435-13-lee.jones@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>