fix(a32nx/fcu): use mach * 100 for selected mach set event

[lukecologne]

Fixes #9881

Summary of Changes

Use Mach * 100 for the FCU_SPD_SET event. As SimConnect event parameters are integers, we have to use this convention to send decimals.

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[lukecologne]

Tested by myself, and works as intended when using the event both in SPD and Mach mode. As it's a very small change I'd say it's fine to merge