Drivers: hv: vmbus: Release cpu lock in error case

In case of invalid sub channel, release cpu lock before returning.

Fixes: a949e86 ("Drivers: hv: vmbus: Resolve race between init_vp_index() and CPU hotplug")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1654794996-13244-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

Author: Saurabh Sengar

drivers/hv/channel_mgmt.c

@@ -639,6 +639,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 		 */
 		if (newchannel->offermsg.offer.sub_channel_index == 0) {
 			mutex_unlock(&vmbus_connection.channel_mutex);
+			cpus_read_unlock();
 			/*
 			 * Don't call free_channel(), because newchannel->kobj
 			 * is not initialized yet.