Input: lifebook - use "static inline" instead of "inline" in lifebook.h

For functions defined in header files we should use static inline rather
than inline, which breaks under the latest upstream gcc (which is really
gcc issue, but static inline is better suited regardless).

The related error (with allmodconfig under tile):

    MODPOST 4002 modules
  ERROR: "lifebook_detect" [drivers/input/mouse/psmouse.ko] undefined!
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/lifebook.h

@@ -16,14 +16,14 @@ void lifebook_module_init(void);
 int lifebook_detect(struct psmouse *psmouse, bool set_properties);
 int lifebook_init(struct psmouse *psmouse);
 #else
-inline void lifebook_module_init(void)
+static inline void lifebook_module_init(void)
 {
 }
-inline int lifebook_detect(struct psmouse *psmouse, bool set_properties)
+static inline int lifebook_detect(struct psmouse *psmouse, bool set_properties)
 {
 	return -ENOSYS;
 }
-inline int lifebook_init(struct psmouse *psmouse)
+static inline int lifebook_init(struct psmouse *psmouse)
 {
 	return -ENOSYS;
 }