mm/vmalloc.c: remove unnecessary return statement

Remove unnecessary return statement for void function.

Link: https://lkml.kernel.org/r/ca23f89259c80c3562700ae6e227b2815a195853.1606891153.git.baolin.wang@linux.alibaba.comSigned-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

@@ -2291,7 +2291,6 @@ static void __vunmap(const void *addr, int deallocate_pages)
 	}
 
 	kfree(area);
-	return;
 }
 
 static inline void __vfree_deferred(const void *addr)