drm/i915: Use a nicer way to lookup the memory region in BIOS FB takeover

Use intel_memory_region_by_type() to find the appropriate memory
region for the BIOS FB takeover.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250313140838.29742-8-ville.syrjala@linux.intel.com


Reviewed-by: Jouni Högander <jouni.hogander@intel.com>