drm/i915/display: Factor out intel_display_{min, max}_pipe_bpp()
Factor out helpers that can be used in a follow-up change to query the
minimum and maximum pipe bpp supported by the HW.
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-10-imre.deak@intel.com