drm/i915/bxt: Force reprogramming a PHY with invalid HW state

It's possible that BIOS enables PHY0, but it programmes only the first
channel on it. Since we program the PHYs only during driver loading this
is an incorrect configuration from the driver's point of view, since we
may use both channels eventually. Detect this scenario and force
reprogramming the PHY in this case.

The actual scenario for me was that the lane optimization for the second
channel in PHY0 was not setup by BIOS and so a state verification
warning was triggered. Everything else was setup properly.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461174366-16758-4-git-send-email-imre.deak@intel.com