feat(MM-DSM). Increase Spektrum/DSM max channels to 16. v2.12.x

[frankiearzu]

Fixes #7631

Summary of changes:

1. Changed Module helper to increase Ch
2. Change multi.c: Add a check that only bits are sent as number of channels, the higher 4 bits are the flags.

Backward compatible; the older firmware will work even when set for Ch13-16.

Latest official MM 1.3.4.63 has a small bug that only supports up to Ch15. There is already a fix for that.

[frankiearzu]

How to test it:

X-Plus channels (13-16), are low resolution, low refresh channels (88ms cycle), so they are good for FlightMode or Gains channels.

1. Assume that you already have a plane with Spektrum SAFE RX configured.
2. In the Mixers, Move/Set your Flight-Mode switch to Ch15.
3. In the Module settings, change the channel range from Ch1 to Ch15.
4. Start DSMTools 2.5 (or later) and go to Forward Programming -> Gyro Setting -> F-Mode Settings and change the FM Ch to Ch15.
5. Now if you move the Ch15 switch, it should change the Flight mode.

Related MM change: Up to Ch15 working in the last MM release v1.3.4.63. Fix to support Ch16 pending merge/release

MultiModule X-Plus channel enhancement here:
pascallanger/DIY-Multiprotocol-TX-Module#1138