drm/i915: Skip FDI vs. dotclock sanity check during readout

drm/i915: Skip FDI vs. dotclock sanity check during readout

The VBIOS/GOP may not program the FDI M/n vs. dotclock entirely
consistently. Eg. on a SNB Thinkpad X220 LVDS I see dotclock of
69.286 MHz (the best the DPLL can do) vs. FDI M/N 69.3 MHz
(matches what the EDID actually declares).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220503182242.18797-15-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>