powerpc/lib: remove memcpy_flushcache redundant return

Align it with other architectures and none of the callers has
been interested its return

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1556278590-14727-1-git-send-email-lirongqing@baidu.com

arch/powerpc/lib/pmem.c

@@ -76,14 +76,12 @@ long __copy_from_user_flushcache(void *dest, const void __user *src,
 	return copied;
 }
 
-void *memcpy_flushcache(void *dest, const void *src, size_t size)
+void memcpy_flushcache(void *dest, const void *src, size_t size)
 {
 	unsigned long start = (unsigned long) dest;
 
 	memcpy(dest, src, size);
 	clean_pmem_range(start, start + size);
-
-	return dest;
 }
 EXPORT_SYMBOL(memcpy_flushcache);