Input: psmouse - fix build error of multiple definition

trackpoint_detect() should be static inline while
CONFIG_MOUSE_PS2_TRACKPOINT is not set, otherwise, we build fails:

drivers/input/mouse/alps.o: In function `trackpoint_detect':
alps.c:(.text+0x8e00): multiple definition of `trackpoint_detect'
drivers/input/mouse/psmouse-base.o:psmouse-base.c:(.text+0x1b50): first defined here
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 55e3d922 ("Input: psmouse - allow disabing certain protocol extensions")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/trackpoint.h

@@ -158,7 +158,8 @@ struct trackpoint_data {
 #ifdef CONFIG_MOUSE_PS2_TRACKPOINT
 int trackpoint_detect(struct psmouse *psmouse, bool set_properties);
 #else
-inline int trackpoint_detect(struct psmouse *psmouse, bool set_properties)
+static inline int trackpoint_detect(struct psmouse *psmouse,
+				    bool set_properties)
 {
 	return -ENOSYS;
 }