ARM: imx: mark .dt_compat as const

Otherwise GCC will mark the .init.rodata section R/W, which causes
a compile error once we add other real R/O data.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>

arch/arm/mach-imx/mach-imx50.c

@@ -23,7 +23,7 @@ static void __init imx50_dt_init(void)
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 }
 
-static const char *imx50_dt_board_compat[] __initconst = {
+static const char * const imx50_dt_board_compat[] __initconst = {
 	"fsl,imx50",
 	NULL
 };