Input: hp_sdc_rtc - fix test in hp_sdc_rtc_read_rt()

If left unsigned the hp_sdc_rtc_read_i8042timer() return value will not
be checked correctly.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/misc/hp_sdc_rtc.c

@@ -209,7 +209,7 @@ static inline int hp_sdc_rtc_read_rt(struct timeval *res) {
 
 /* Read the i8042 fast handshake timer */
 static inline int hp_sdc_rtc_read_fhs(struct timeval *res) {
-	uint64_t raw;
+	int64_t raw;
 	unsigned int tenms;
 
 	raw = hp_sdc_rtc_read_i8042timer(HP_SDC_CMD_LOAD_FHS, 2);