drm/i915: Dump more configuration information for DSI

Dump out more of the DSI configuration details during init.
This includes pclk, burst_mode_ratio, lane_count, pixel_overlap,
video_mode_format and reset_timer_val.

v2: Dump more info (Chris)
v3: Use the VIDEO_MODE_ defines for consistency (Chris)
    Dump dphy_reg too (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161221143114.23530-1-ville.syrjala@linux.intel.com