selftests/mm: sigbus-wp test requires UFFD_FEATURE_WP_HUGETLBFS_SHMEM

The sigbus-wp test requires the UFFD_FEATURE_WP_HUGETLBFS_SHMEM flag for
shmem and hugetlb targets.  Otherwise it is not backwards compatible with
kernels <5.19 and fails with EINVAL.

Link: https://lkml.kernel.org/r/20240321232023.2064975-1-edliaw@google.com
Fixes: 73c1ea93

 ("selftests/mm: move uffd sig/events tests into uffd unit tests")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Peter Xu <peterx@redhat.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>