drm/panfrost: Set IOMMU_CACHE flag

Panfrost does not support uncached mappings, so flag them properly. Also
flag the pages that are mapped as response to a page fault as cached.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250324185801.168664-2-ariel.dalessandro@collabora.com