drm/i915/bios: Use the cached BDB version

We have the BDB version cached, use it. We're going to have to
start doing some of the BDB block parsing later, at which point
we may no longer have the VBT around anymore (we free it at the
end of intel_bios_init() when it didn't come via OpRegion).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405173410.11436-2-ville.syrjala@linux.intel.com


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