Parametrize the FBC_CONTROL bits for neater code.

Also add the one missing bit: "stop compression on modification".
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200429101034.8208-9-ville.syrjala@linux.intel.comReviewed-by: José Roberto de Souza <jose.souza@intel.com>