ARM: imx: mach-mx31lite: Make mx31lite_map_io static

The following build warning is seen with W=1:

warning: no previous prototype for ‘mx31lite_map_io’
[-Wmissing-prototypes] void __init mx31lite_map_io(void)

This function is only used in this file so make it "static".
Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/mach-imx/mach-mx31lite.c

@@ -245,7 +245,7 @@ static struct map_desc mx31lite_io_desc[] __initdata = {
 /*
  * Set up static virtual mappings.
  */
-void __init mx31lite_map_io(void)
+static void __init mx31lite_map_io(void)
 {
 	mx31_map_io();
 	iotable_init(mx31lite_io_desc, ARRAY_SIZE(mx31lite_io_desc));