s390: fix typo in linker script

Rename amod31 to amode31 like it was supposed to be.

Fixes: c78d0c74 ("s390: rename dma section to amode31")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/kernel/vmlinux.lds.S

@@ -74,7 +74,7 @@ SECTIONS
 	BOOT_DATA_PRESERVED
 
 	. = ALIGN(8);
-	.amod31.refs : {
+	.amode31.refs : {
 		_start_amode31_refs = .;
 		*(.amode31.refs)
 		_end_amode31_refs = .;