lmb: staticise lmb_add_memory()

lmb_add_memory() is only called from the lmb module. Mark the function
as static.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/lmb.c b/lib/lmb.c
index a30ae64..3265fad 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -605,7 +605,7 @@
 	}
 }
 
-void lmb_add_memory(void)
+static void lmb_add_memory(void)
 {
 	int i;
 	phys_addr_t bank_end;