drivers:hv: Make a function to free mmio regions through vmbus

BugLink: http://bugs.launchpad.net/bugs/1616677

This patch introduces a function that reverses everything
done by vmbus_allocate_mmio().  Existing code just called
release_mem_region().  Future patches in this series
require a more complex sequence of actions, so this function
is introduced to wrap those actions.
Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(back ported from commit 97fb77dc)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

 Conflicts:
	drivers/hv/vmbus_drv.c
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>

drivers/hv/vmbus_drv.c

@@ -1252,17 +1252,7 @@ EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
  */
 void vmbus_free_mmio(resource_size_t start, resource_size_t size)
 {
-	struct resource *iter;
-
-	down(&hyperv_mmio_lock);
-	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
-		if ((iter->start >= start + size) || (iter->end <= start))
-			continue;
-
-		__release_region(iter, start, size);
-	}
 	release_mem_region(start, size);
-	up(&hyperv_mmio_lock);
 
 }
 EXPORT_SYMBOL_GPL(vmbus_free_mmio);