mx51: add imx_keypad device definition for mx51 platforms

add imx_keypad platform device definition and clocks for mx51
platforms.

Signed-off-by: Jason Wang <jason77.wang@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/mach-mx5/devices.h b/arch/arm/mach-mx5/devices.h
index a853933..e509cfa 100644
--- a/arch/arm/mach-mx5/devices.h
+++ b/arch/arm/mach-mx5/devices.h
@@ -9,3 +9,4 @@
 extern struct platform_device mxc_i2c_device0;
 extern struct platform_device mxc_i2c_device1;
 extern struct platform_device mxc_hsi2c_device;
+extern struct platform_device mxc_keypad_device;