samples: tfm: Update tag to run tests on module change

A recent change #61718, adds support to the twister build to check for
manifest changes, and run tests using tags based on the modules that have
changed.  The tfm tests have an existing tag `tfm` to select these tests,
but the above patch uses a tag named after the module, trusted-firmware-m.
To make this work, add `trusted-firmware-m` in addition to the existing tag
`tfm` so that these tests will run whenever the tfm module is updated.

Signed-off-by: David Brown <david.brown@linaro.org>