Input: surface3_spi - remove set but unused variable 'timestamp'

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

 drivers/input/touchscreen/surface3_spi.c: In function ‘surface3_spi_process_touch’:
 drivers/input/touchscreen/surface3_spi.c:97:6: warning: variable ‘timestamp’ set but not used [-Wunused-but-set-variable]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20210114152323.2382283-5-lee.jones@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/surface3_spi.c

@@ -94,9 +94,7 @@ static void surface3_spi_report_touch(struct surface3_ts_data *ts_data,
 
 static void surface3_spi_process_touch(struct surface3_ts_data *ts_data, u8 *data)
 {
-	u16 timestamp;
 	unsigned int i;
-	timestamp = get_unaligned_le16(&data[15]);
 
 	for (i = 0; i < 13; i++) {
 		struct surface3_ts_data_finger *finger;