arm: Include asm/setup.h explictly

Include this header where needed so we do not need to rely on common.h.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/include/asm/omap_common.h b/arch/arm/include/asm/omap_common.h
index c1a70b1..f989983 100644
--- a/arch/arm/include/asm/omap_common.h
+++ b/arch/arm/include/asm/omap_common.h
@@ -638,6 +638,8 @@
 	       u32 txdone, u32 txdone_mask, u32 opp);
 s8 abb_setup_ldovbb(u32 fuse, u32 ldovbb);
 
+struct tag_serialnr;
+
 void omap_die_id_serial(void);
 void omap_die_id_get_board_serial(struct tag_serialnr *serialnr);
 void omap_die_id_usbethaddr(void);