drm/i915: Reject X/Y tiled BIOS FB if we don't have fenced regions

drm/i915: Reject X/Y tiled BIOS FB if we don't have fenced regions

The CPU always needs linear view into the BIOS FB, and for X/Y tiled
buffers that is achieved by the use of a fenced region. If the
underlying driver doesn't support fenced regions then we can't keep
the X/Y tiled BIOS FB. i915 has fenced regions, xe does not.

Probably not a big deal since I don't think we've seen tiled BIOS
FBs outside of some MacBooks. See eg. commit d9a515867bdb
("drm/i915/gen9+: Fix initial readout for Y tiled framebuffers").

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260410150449.9699-9-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>