common: board_f: Make reserve_mmu a weak function

Make reserve_mmu a weak so that it provides an option
to customize this routine as per platform need

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/board_f.c b/common/board_f.c
index 19b8055..5915e50 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -340,7 +340,7 @@
 }
 
 #ifdef CONFIG_ARM
-static int reserve_mmu(void)
+__weak int reserve_mmu(void)
 {
 #if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
 	/* reserve TLB table */