drm/i915/chv: Add phy supports for Cherryview

drm/i915/chv: Add phy supports for Cherryview

Added programming phy layer for CHV based on "Application note for 1273
CHV Display phy".

v2: Rebase the code and do some cleanup.
v3: Rework based on Ville review.
    -Fix the macro where the ch info need to swap, and add parens to ?
	 operator.
	-Fix wrong bit define for DPIO_PCS_SWING_CALC_0 and
	 DPIO_PCS_SWING_CALC_1 and rename for meaningful.
    -Add some comments for CHV specific DPIO registers.
    -Change the dp margin registery value to decimal to align with the
	 doc.
	-Fix the not clearing some value in vlv_dpio_read before write again.
    -Create new hdmi/dp encoder function for chv instead of share with
	valleyview.
v4: Rebase the code after rename the DPIO registers define and upstream
	change.
    Based on Ville review.
    -For unique transition scale selection, after Ville point out, look
	 like the doc might wrong for the bit 26.  Use bit 27 for ch0 and
	 ch1.
	-Break up some dpio write value into two/three steps for readability.
	-Remove unrelated change.
    -Add some shift define for some registers instead just give the hex
	value.
    -Fix a bug where write to wrong VLV_TX_DW3.
v5: Based on Ville review.
	- Move tx lane latency optimal setting from chv_dp_pre_pll_enable to
	  chv_pre_enable_dp, and chv_hdmi_pre_pll_enable to
	  chv_hdmi_pre_enable respectively.
 	- Fix typo in one margin_reg_value for DP_TRAIN_VOLTAGE_SWING_400.
	- Clear DPIO_TX_UNIQ_TRANS_SCALE_EN for DP and HDMI.
	- Mask the old deemph and swing bits for hdmi.
v6: Remove stub for pre_pll_enable for dp and hdmi.

Signed-off-by: Chon Ming Lee <chon.ming.lee@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[vsyrjala: Don't touch panel power sequencing on DP]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>