drm/i915/fbc: Nuke BDW_FBC_COMP_SEG_MASK

Just use a same mask for ivb/hsw as for bdw+. The extra bit
in the bdw mask is mbz on ivb/hsw anyway so this is just
pointless complexity.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211104144520.22605-12-ville.syrjala@linux.intel.com
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>