drm/dp: add some new DP regs for DP 1.2

#define DP_MAX_LANE_COUNT                   0x002

# define DP_MAX_LANE_COUNT_MASK		    0x1f

# define DP_TPS3_SUPPORTED		    (1 << 6)

# define DP_ENHANCED_FRAME_CAP		    (1 << 7)

#define DP_MAX_DOWNSPREAD                   0x003

#define DP_MAIN_LINK_CHANNEL_CODING         0x006

#define DP_TRAINING_AUX_RD_INTERVAL         0x00e

/* link configuration */

#define	DP_LINK_BW_SET		            0x100

# define DP_LINK_BW_1_62		    0x06

# define DP_LINK_BW_2_7			    0x0a

# define DP_LINK_BW_5_4			    0x14

#define DP_LANE_COUNT_SET	            0x101

# define DP_LANE_COUNT_MASK		    0x0f

# define DP_TRAINING_PATTERN_DISABLE	    0

# define DP_TRAINING_PATTERN_1		    1

# define DP_TRAINING_PATTERN_2		    2

# define DP_TRAINING_PATTERN_3		    3

# define DP_TRAINING_PATTERN_MASK	    0x3

# define DP_LINK_QUAL_PATTERN_DISABLE	    (0 << 2)