ARM: imx: fix imx31-dt.c time-related warning

Commit 6bb27d73 "ARM: delete struct sys_timer" caused the following:

arch/arm/mach-imx/imx31-dt.c:56:2: warning: initialization from incompatible pointer type [enabled by default]
arch/arm/mach-imx/imx31-dt.c:56:2: warning: (near initialization for ‘__mach_desc_IMX31_DT.init_time’) [enabled by default]

This is because mx31_clocks_init_dt() returns int, whereas the .init_time
field prototype expects a function returning void. Implement a wrapper so
that the prototypes match.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NOlof Johansson <olof@lixom.net>

arch/arm/mach-imx/imx31-dt.c

@@ -43,12 +43,17 @@ static const char *imx31_dt_board_compat[] __initdata = {
 	NULL
 };
 
+static void __init imx31_dt_timer_init(void)
+{
+	mx31_clocks_init_dt();
+}
+
 DT_MACHINE_START(IMX31_DT, "Freescale i.MX31 (Device Tree Support)")
 	.map_io		= mx31_map_io,
 	.init_early	= imx31_init_early,
 	.init_irq	= mx31_init_irq,
 	.handle_irq	= imx31_handle_irq,
-	.init_time	= mx31_clocks_init_dt,
+	.init_time	= imx31_dt_timer_init,
 	.init_machine	= imx31_dt_init,
 	.dt_compat	= imx31_dt_board_compat,
 	.restart	= mxc_restart,