drm/i915/fbc: Store the fbc1 compression interval in the params

Avoid the FBC_CONTROL rmw and just store the fbc compression
interval in the params/

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200429101034.8208-10-ville.syrjala@linux.intel.com


Reviewed-by: José Roberto de Souza <jose.souza@intel.com>