modsign: add symbol prefix to certificate list

Add the arch symbol prefix (if applicable) to the asm definition of
modsign_certificate_list and modsign_certificate_list_end. This uses the
recently defined SYMBOL_PREFIX which is derived from
CONFIG_SYMBOL_PREFIX.

This fixes the build of module signing on the blackfin and metag
architectures.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

kernel/modsign_pubkey.c

@@ -21,10 +21,10 @@ struct key *modsign_keyring;
 extern __initdata const u8 modsign_certificate_list[];
 extern __initdata const u8 modsign_certificate_list_end[];
 asm(".section .init.data,\"aw\"\n"
-    "modsign_certificate_list:\n"
+    SYMBOL_PREFIX "modsign_certificate_list:\n"
     ".incbin \"signing_key.x509\"\n"
     ".incbin \"extra_certificates\"\n"
-    "modsign_certificate_list_end:"
+    SYMBOL_PREFIX "modsign_certificate_list_end:"
     );
 
 /*