global: Change the IF statement to a SWITCH statement

[muramura]

Solved Problem

The same variable was being compared with multiple values. The same variable was compared with different decision values.

Solution

From IF statement to SWITCH statement.

Changelog Entry

None

Alternatives

None

Test coverage

None

Context

None

[muramura]

I also changed MAVLINK_MISSION. I think SWITCH statement is better to select the process in the state.