intelfb: add preliminary i2c support

#define FW_DISPC_BL_SHIFT		8

#define FW_DISPC_BL_MASK		0x7

#define GPIOA             0x5010

#define GPIOB             0x5014

#define GPIOC             0x5018 // this may be external DDC on i830

#define GPIOD             0x501C // this is DVO DDC

#define GPIOE             0x5020 // this is DVO i2C

#define GPIOF             0x5024

/* PLL registers */

#define VGA0_DIVISOR		0x06000