powerpc: Exported functions __clear_user and copy_page use r2 so need _GLOBAL_TOC()

__clear_user and copy_page load from the TOC and are also exported
to modules. This means we have to use _GLOBAL_TOC() so that we
create the global entry point that sets up the TOC.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/lib/string_64.S b/arch/powerpc/lib/string_64.S
index 3b1e480..7bd9549 100644
--- a/arch/powerpc/lib/string_64.S
+++ b/arch/powerpc/lib/string_64.S
@@ -77,7 +77,7 @@
 	mr	r3,r4
 	blr
 
-_GLOBAL(__clear_user)
+_GLOBAL_TOC(__clear_user)
 	cmpdi	r4,32
 	neg	r6,r3
 	li	r0,0