char: hpet: Remove unused variable 'm'

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

 drivers/char/hpet.c: In function ‘hpet_interrupt’:
 drivers/char/hpet.c:159:17: warning: variable ‘m’ set but not used [-Wunused-but-set-variable]

Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Bob Picco <robert.picco@hp.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210520121347.3467794-13-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/hpet.c

@@ -156,12 +156,12 @@ static irqreturn_t hpet_interrupt(int irq, void *data)
 	 * This has the effect of treating non-periodic like periodic.
 	 */
 	if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) {
-		unsigned long m, t, mc, base, k;
+		unsigned long t, mc, base, k;
 		struct hpet __iomem *hpet = devp->hd_hpet;
 		struct hpets *hpetp = devp->hd_hpets;
 
 		t = devp->hd_ireqfreq;
-		m = read_counter(&devp->hd_timer->hpet_compare);
+		read_counter(&devp->hd_timer->hpet_compare);
 		mc = read_counter(&hpet->hpet_mc);
 		/* The time for the next interrupt would logically be t + m,
 		 * however, if we are very unlucky and the interrupt is delayed