selftests: ncdevmem: Run selftest when none of the -s or -c has been provided

selftests: ncdevmem: Run selftest when none of the -s or -c has been provided

This will be used as a 'probe' mode in the selftest to check whether
the device supports the devmem or not. Use hard-coded queue layout
(two last queues) and prevent user from passing custom -q and/or -t.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20241107181211.3934153-11-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>