Drivers: hv: rename sc_lock to the more generic lock

sc_lock spinlock in struct vmbus_channel is being used to not only protect the
sc_list field, e.g. vmbus_open() function uses it to implement test-and-set
access to the state field. Rename it to the more generic 'lock' and add the
description.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 18c4f23..2978f5e 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -73,14 +73,14 @@
 	unsigned long flags;
 	int ret, t, err = 0;
 
-	spin_lock_irqsave(&newchannel->sc_lock, flags);
+	spin_lock_irqsave(&newchannel->lock, flags);
 	if (newchannel->state == CHANNEL_OPEN_STATE) {
 		newchannel->state = CHANNEL_OPENING_STATE;
 	} else {
-		spin_unlock_irqrestore(&newchannel->sc_lock, flags);
+		spin_unlock_irqrestore(&newchannel->lock, flags);
 		return -EINVAL;
 	}
-	spin_unlock_irqrestore(&newchannel->sc_lock, flags);
+	spin_unlock_irqrestore(&newchannel->lock, flags);
 
 	newchannel->onchannel_callback = onchannelcallback;
 	newchannel->channel_callback_context = context;