memremap: merge find_dev_pagemap into get_dev_pagemap

There is only one caller of the trivial function find_dev_pagemap left,
so just merge it into the caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

kernel/memremap.c

@@ -306,14 +306,6 @@ static void devm_memremap_pages_release(void *data)
 		      "%s: failed to free all reserved pages\n", __func__);
 }
 
-/* assumes rcu_read_lock() held at entry */
-static struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
-{
-	WARN_ON_ONCE(!rcu_read_lock_held());
-
-	return radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys));
-}
-
 /**
  * devm_memremap_pages - remap and provide memmap backing for the given resource
  * @dev: hosting device for @res
@@ -466,7 +458,7 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 
 	/* fall back to slow path lookup */
 	rcu_read_lock();
-	pgmap = find_dev_pagemap(phys);
+	pgmap = radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys));
 	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
 		pgmap = NULL;
 	rcu_read_unlock();