Baro and Mag driver check for I2C bus being busy

[SteveCEvans]

May fix: #13497

Please test.

[github-actions]

Do you want to test this code? You can flash it directly from Betaflight Configurator:

• Simply put #13509 (this pull request number) in the Select commit field of the Configurator firmware flasher tab (you need to Enable expert mode, Show release candidates and Development).

WARNING: It may be unstable. Use only for testing!

[haslinghuis]

SITL (virtual barometer) needs to be fixed but fix can be tested for other targets.

[ledvinap]

(not tested yet, but looks good)

[ledvinap]

Maybe code it this way (continue only is operation succeeds):

Suggested change

	if (busReadRegisterBufferStart(dev, AK8975_MAG_REG_ST1, &status, sizeof(status))) {
	state = STATE_WAIT_STATUS1;
	}
	if (!busReadRegisterBufferStart(dev, AK8975_MAG_REG_ST1, &status, sizeof(status))) {
	return false;
	}
	state = STATE_WAIT_STATUS1;

[SteveCEvans]

That would still require a return false following the state assignment.

[ledvinap]

The logic is:
If operation fails, return false to retry soon
Set next state
Return false to call next state faster

first and second false have a bit different meaning.
And it is more similar to longer cases - return of something fails, continue othervise.

But resulting instructions are the same and your variant is shorter. It is only minor stylistics suggestion..

[ledvinap]

@SteveCEvans : It should fix #13497
It will also retry some I2C operations on NAK (only addr+reg address part in background mode). That may help considerably on noisy I2C.

[SteveCEvans]

Thanks @ledvinap for your insightful review comments as always.