sh: allow romImage data between head.S and the zero page

Extend the romImage code to allow putting data between
the head.S file and the empty_zero_page. Needed in the
case of more advanced loader code in a separate C file.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/boot/romimage/vmlinux.scr

@@ -1,6 +1,7 @@
 SECTIONS
 {
   .text : {
+	zero_page_pos = .;
 	*(.data)
 	}
 }