Rover: Use common variables

[muramura]

Common variables G and G2 are used.
G and G2 are used directly.

Mixed in the same file.
I think it would be better to unify common variables.

[khancyr]

LGTM

[peterbarker]

Looks good but vehicle maintainer has to approve

[IamPete1]

Looks good, but does cost a little flash, MatekF405:

Binary Name      Text [B]       Data [B]     BSS (B)      Total Flash Change [B] (%)      Flash Free After PR (B)
---------------  -------------  -----------  -----------  ----------------------------  -------------------------
ardusub          0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                      187812
antennatracker   0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                      343888
arducopter-heli  0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                       82464
ardurover        48 (+0.0059%)  0 (0.0000%)  0 (0.0000%)  48 (+0.0059%)                                    174268
blimp            0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                      325092
arduplane        0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                       49384
arducopter       0 (0.0000%)    0 (0.0000%)  0 (0.0000%)  0 (0.0000%)                                       93632