swiotlb: remove a useless return in swiotlb_init

Both swiotlb_init_remap() and swiotlb_init() have return type void.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/swiotlb.c

@@ -282,7 +282,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
 
 void __init swiotlb_init(bool addressing_limit, unsigned int flags)
 {
-	return swiotlb_init_remap(addressing_limit, flags, NULL);
+	swiotlb_init_remap(addressing_limit, flags, NULL);
 }
 
 /*