Fix `hosted/cli.c`, minor implicit fallthrough

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Detailed description

• Not a feature
• Since #1871 when libgpiod-dev is installed on build host, a warning is emitted.
• This PR solves it by terminating both cases with a break.

CMSIS-DAP and GPIOD backends are runtime mutually exclusive, so it was not critical, but also nobody picked it up, so I'll clean it up myself.

Your checklist for this pull request

• [x] I've read the Code of Conduct
• [x] I've read the guidelines for contributing to this repository
• [x] It builds for hardware native (see Building the firmware) and should not affect it
• [x] It builds as BMDA (see Building the BMDA)
• [x] I've tested it to the best of my ability
• [x] My commit messages provide a useful short description of what the commits do

Closing issues