PM / Runtime: Fix runtime accounting calculation error

With delta type being int, its value is made zero
for all values of now > 0x80000000.
Hence fixing it.

Signed-off-by: venu byravarasu <vbyravarasu@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 6bb3aaf..18ef87e 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -29,13 +29,10 @@
 void update_pm_runtime_accounting(struct device *dev)
 {
 	unsigned long now = jiffies;
-	int delta;
+	unsigned long delta;
 
 	delta = now - dev->power.accounting_timestamp;
 
-	if (delta < 0)
-		delta = 0;
-
 	dev->power.accounting_timestamp = now;
 
 	if (dev->power.disable_depth > 0)