accel/amdxdna: Remove mmap and export support for ubuf

accel/amdxdna: Remove mmap and export support for ubuf

Ubuf pages should not be mmaped or exported. Remove the ubuf mmap callback
and return -EOPNOTSUPP when exporting ubuf objects.

ubuf vmap is also removed for there is not a real use case yet.

Fixes: bd72d4acda10 ("accel/amdxdna: Support user space allocated buffer")
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260518155706.937461-1-lizhi.hou@amd.com