drm/i915: Beef up the IPS vs. CRC workaround

Oneshot disabling of IPS when CRC capturing is started is insufficient.
IPS may get re-enabled by any plane update, and hence tests that keep
CRC capturing on across plane updates will start to see inconsistent
results as soon as IPS kicks back in. Add a new knob into the crtc state
to make sure IPS stays disabled as long as CRC capturing is enabled.

Forcing a modeset is the easiest way to handle this since that's already
how we do the panel fitter workaround. It's a little heavy handed just
for IPS, but seeing as we might already do the panel fitter workaround
I think it's better to follow that. We migth want to optimize both cases
later if someone gets too upset by the extra delay from the modeset.

v2: Check the right thing when deciding whether to force a modeset
v3: Rebase, check HAS_IPS before forcing a modeset,
    move ips_force_disable check into pipe_config_supports_ips()

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Marta Lofstedt <marta.lofstedt@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101664


Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: Marta Lofsted <marta.lofstedt@intel.com> #v2
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170817145509.15549-1-ville.syrjala@linux.intel.com