Revert "IB/rxe: Mark Soft-RoCE Transport driver as tech-preview"

This reverts commit c54211b70e8e9f062803f03c9fa5906d8d5ca02c.

The driver was disabled in this MR:
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1299

As such we don't need anymore to mark it as tech preview.

Signed-off-by: Herton R. Krzesinski <herton@redhat.com>