drm/i915: Fix frame start delay programming

drm/i915: Fix frame start delay programming

Currently we're blindly poking at the frame start delay bits
in PIPECONF when trying to sanitize the hardware state. Those
bits decided to move elsewhere on HSW, so on many platforms
we're not doing anything at all here. Also we're forgetting
about the PCH transcoder entirely.

Add all the bit definitions for the various homes these bits
have had throughout the years, and reset them all to zero.

However I'm not entirely sure this is a safe thing to do. If
not I guess we'd want full readout+statecheck for this stuff.
For now let's stick to the current logic and hope for the
best.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191024122138.25065-3-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>