zynq: timer: Fix wrong timer calculation

Fix wrong timer calculation in get_timer_masked incase of
overflow.
This fixes the issue of getting wrong time from get_timer()
calls.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/cpu/armv7/zynq/timer.c

@@ -93,7 +93,9 @@ ulong get_timer_masked(void)
 		gd->arch.tbl += gd->arch.lastinc - now;
 	} else {
 		/* We have an overflow ... */
-		gd->arch.tbl += gd->arch.lastinc + TIMER_LOAD_VAL - now + 1;
+		gd->arch.tbl += gd->arch.lastinc + (TIMER_LOAD_VAL /
+				(gd->arch.timer_rate_hz / CONFIG_SYS_HZ)) -
+				now + 1;
 	}
 	gd->arch.lastinc = now;