i2c: Add viperboard i2c master driver

This adds the mfd cell to use the i2c part of the Nano River Technologies
viperboard as i2c master.

Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
index 42d339f..ef78514 100644
--- a/include/linux/mfd/viperboard.h
+++ b/include/linux/mfd/viperboard.h
@@ -42,6 +42,8 @@
 #define VPRBRD_USB_TYPE_OUT	    0x40
 #define VPRBRD_USB_TYPE_IN	    0xc0
 #define VPRBRD_USB_TIMEOUT_MS       100
+#define VPRBRD_USB_REQUEST_I2C_FREQ 0xe6
+#define VPRBRD_USB_REQUEST_I2C      0xe9
 #define VPRBRD_USB_REQUEST_MAJOR    0xea
 #define VPRBRD_USB_REQUEST_MINOR    0xeb
 #define VPRBRD_USB_REQUEST_GPIOA    0xed