ARC: export clear_user_page() for modules

stable inclusion
from stable-5.10.68
commit f5176a0798bd286a1fb2061a28f136fe1fdb0cc2
bugzilla: 182671 https://gitee.com/openeuler/kernel/issues/I4EWUH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f5176a0798bd286a1fb2061a28f136fe1fdb0cc2

--------------------------------

[ Upstream commit 6b5ff040 ]

0day bot reports a build error:
  ERROR: modpost: "clear_user_page" [drivers/media/v4l2-core/videobuf-dma-sg.ko] undefined!
so export it in arch/arc/ to fix the build error.

In most ARCHes, clear_user_page() is a macro. OTOH, in a few
ARCHes it is a function and needs to be exported.
PowerPC exported it in 2004. It looks like nds32 and nios2
still need to have it exported.

Fixes: 4102b533 ("ARC: [mm] Aliasing VIPT dcache support 2/4")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Reported-by: Nkernel test robot <lkp@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: NVineet Gupta <vgupta@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arc/mm/cache.c

@@ -1123,7 +1123,7 @@ void clear_user_page(void *to, unsigned long u_vaddr, struct page *page)
 	clear_page(to);
 	clear_bit(PG_dc_clean, &page->flags);
 }
-
+EXPORT_SYMBOL(clear_user_page);
 
 /**********************************************************************
  * Explicit Cache flush request from user space via syscall