AP_MSP: MSP_RAW_GPS cog should be decidegrees not centidegrees

[catkira]

source: http://www.multiwii.com/wiki/index.php?title=Multiwii_Serial_Protocol

[catkira]

I think we should also make ground_course_dd uint16_t, because the range is 0 - 3600 deci-degrees. I agree that having centi-degrees would be smarter, because it could still fit into a 16-bit number, but just doing it differently here causes incompatibility issues.

[peterbarker]

Looks likely.

Commit message should be AP_MSP:, not fix:. Want to fix that or shall I?

[catkira]

I can fix. Should I also change it to uint16_t? (-> see my last force push)

[catkira]

@rmackay9 can you backport this to plane 4.5.6 ?