Gimbal page resets camera trigger if there is more than one.

This is a rather annoying bug that had me going crazy for a little bit.

If you open the "Gimbal" Page under Initial setup and you have more than 1 RC channel as a camera trigger (Set to 10 for RC_Function) Mission planner will automatically set one of those RC Channels to 0 as soon as you click on the Gimbal page.

Reproduce the issue by opening the Gimbal page under Initial setup with more than one RC channel assigned to RC_Function 10, then trace the Gimbal page code that updates camera-trigger channels. Done means opening that page no longer changes any configured trigger channel to 0; verify the behavior with multiple camera-trigger channels.

Written by the indexing model from the issue text.