drm/i915: Reject modeset if the dotclock is too high

Reject the modeset if the requested dotclock exceeds the maximum allowed
by the hardware. So far we've only checked this on gen2/3 while also
handling the double wide vs. single wide pipe selection. Extend the
check to all platforms since we have the max dotclock correctly
populated now across the board.

Testcase: igt/kms_invalid_dotclock
Cc: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464114859-15610-1-git-send-email-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>