ARM: mx5: dynamically allocate imx-keypad devices

Add support for dynamical allocation of imx-keypad on mx5 platform.

After moving to dynamically registration of the keypad, the keypad clock
name needs to change accordingly.

The reason is that the original mx5 keypad platform_device id was 0,
now we use id=-1 as per arch/arm/plat-mxc/devices/platform-imx-keypad.c.

Tested keypad successfully on a MX51_3DS board.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/mach-mx5/devices-imx51.h b/arch/arm/mach-mx5/devices-imx51.h
index 39183ee..531f454 100644
--- a/arch/arm/mach-mx5/devices-imx51.h
+++ b/arch/arm/mach-mx5/devices-imx51.h
@@ -51,3 +51,7 @@
 extern const struct imx_mxc_pwm_data imx51_mxc_pwm_data[] __initconst;
 #define imx51_add_mxc_pwm(id, pdata)	\
 	imx_add_mxc_pwm(&imx51_mxc_pwm_data[id], pdata)
+
+extern const struct imx_imx_keypad_data imx51_imx_keypad_data __initconst;
+#define imx51_add_imx_keypad(pdata)	\
+	imx_add_imx_keypad(&imx51_imx_keypad_data, pdata)