ARM: imx: dynamically allocate mxc_w1 devices

Currently there is no platform data used in the driver.  In case this
changes NULL is passed unused to the soc specific functions.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
diff --git a/arch/arm/mach-mx3/mach-pcm037.c b/arch/arm/mach-mx3/mach-pcm037.c
index 86e86c1..bc5d3a1 100644
--- a/arch/arm/mach-mx3/mach-pcm037.c
+++ b/arch/arm/mach-mx3/mach-pcm037.c
@@ -614,7 +614,7 @@
 	imx31_add_imx_uart1(&uart_pdata);
 	imx31_add_imx_uart2(&uart_pdata);
 
-	mxc_register_device(&mxc_w1_master_device, NULL);
+	imx31_add_mxc_w1(NULL);
 
 	/* LAN9217 IRQ pin */
 	ret = gpio_request(IOMUX_TO_GPIO(MX31_PIN_GPIO3_1), "lan9217-irq");