Input: melfas_mip4 - mark a bunch of variables as __always_unused

Dmitry requested to keep these around for the purposes of documentation.

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

 drivers/input/touchscreen/melfas_mip4.c: In function ‘mip4_report_touch’:
 drivers/input/touchscreen/melfas_mip4.c:474:5: warning: variable ‘size’ set but not used [-Wunused-but-set-variable]
 drivers/input/touchscreen/melfas_mip4.c:472:5: warning: variable ‘pressure_stage’ set but not used [-Wunused-but-set-variable]
 drivers/input/touchscreen/melfas_mip4.c:469:7: warning: variable ‘palm’ set but not used [-Wunused-but-set-variable]
 drivers/input/touchscreen/melfas_mip4.c:468:7: warning: variable ‘hover’ set but not used [-Wunused-but-set-variable]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210114152323.2382283-3-lee.jones@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/melfas_mip4.c

@@ -465,13 +465,13 @@ static void mip4_report_keys(struct mip4_ts *ts, u8 *packet)
 static void mip4_report_touch(struct mip4_ts *ts, u8 *packet)
 {
 	int id;
-	bool hover;
-	bool palm;
+	bool __always_unused hover;
+	bool __always_unused palm;
 	bool state;
 	u16 x, y;
-	u8 pressure_stage = 0;
+	u8 __always_unused pressure_stage = 0;
 	u8 pressure;
-	u8 size;
+	u8 __always_unused size;
 	u8 touch_major;
 	u8 touch_minor;