accel/amdxdna: Fix iommu domain lifetime race during device removal

accel/amdxdna: Fix iommu domain lifetime race during device removal

When force_iova mode is enabled, amdxdna_remove() frees xdna->domain. If
amdxdna_gem_obj_free() is called after device removal, it may attempt to
access xdna->domain, resulting in a use-after-free.

Fix the race by adding freeing xdna->domain as a managed release action,
so its lifetime is managed by DRM and remains valid until all managed
resources are released.

Fixes: ece3e8980907 ("accel/amdxdna: Allow forcing IOVA-based DMA via module parameter")
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260611055150.3070216-3-lizhi.hou@amd.com