Fix #126, Refactor CFE_PSP_ModuleType_t enum

[skliper]

Describe the contribution
Fix #126 - Avoids irregular enum warning

Testing performed
Build bundle and unit test (passed)

Expected behavior changes
None other than eliminates static analysis warning

System(s) tested on

• Hardware: cFS Dev Server
• OS: Ubuntu 18.04
• Versions: Bundle main + this commit

Additional context
None

Third party code
None

Contributor Info - All information REQUIRED for consideration of pull request
Jacob Hageman - NASA/GSFC

[astrogeco]

CCB:2021-01-13 CHANGE

Invalid should stay zero.
Could make it sequential.

[skliper]

Updated/simplified... could evolve to a switch or whatever if extended, but behavior is the same w/ just a simple equality check at this point.

[jphickey]

This is fine.

Just a note that the reason there was a "range" instead of just a single value it was intended to have more than one, it just ended up that the "SIMPLE" was the only module type that made it into the common framework code. For instance there are some old projects I did where we had two types, "SIMPLE" and "DEVICE_DRIVER" - the latter provided a useful layer to abstract our low level device I/O on a per-platform basis - but this type isn't in the common framework now, of course. But probably a "switch" would be better there anyway.