lmb: only force on arches that use it

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/lmb.h b/include/lmb.h
index 14e8727..43082a3 100644
--- a/include/lmb.h
+++ b/include/lmb.h
@@ -52,6 +52,10 @@
 {
 	return type->region[region_nr].size;
 }
+
+void board_lmb_reserve(struct lmb *lmb);
+void arch_lmb_reserve(struct lmb *lmb);
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_LMB_H */