vmbus: use kernel bitops for traversing interrupt mask

Use standard kernel operations for find first set bit to traverse
the channel bit array. This has added benefit of speeding up
lookup on 64 bit and because it uses find first set instruction.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/vmbus_drv.c

@@ -908,10 +908,8 @@ static void vmbus_isr(void)
 		(vmbus_proto_version == VERSION_WIN7)) {
 
 		/* Since we are a child, we only need to check bit 0 */
-		if (sync_test_and_clear_bit(0,
-			(unsigned long *) &event->flags32[0])) {
+		if (sync_test_and_clear_bit(0, event->flags))
 			handled = true;
-		}
 	} else {
 		/*
 		 * Our host is win8 or above. The signaling mechanism