metag: export clear_page and copy_page

Various file systems use clear_page() and copy_page(), so when they're
built as modules we get build errors like the following:

ERROR: "clear_page" [fs/ntfs/ntfs.ko] undefined!
ERROR: "copy_page" [fs/nilfs2/nilfs2.ko] undefined!

Therefore export these functions to modules from metag_ksyms.c to fix
the errors. This was hit by a randconfig build.
Signed-off-by: James Hogan <james.hogan@imgtec.com>

arch/metag/kernel/metag_ksyms.c

@@ -37,6 +37,8 @@ EXPORT_SYMBOL(get_trigger_mask);
 EXPORT_SYMBOL(global_trigger_mask);
 #endif
 
+EXPORT_SYMBOL(clear_page);
+EXPORT_SYMBOL(copy_page);
 EXPORT_SYMBOL(empty_zero_page);
 
 EXPORT_SYMBOL(pfn_base);