Consolidation of issues about RM3100 compass

[and-sh]

Using the compass revealed the following problems:

1. Due to incorrect scaling most of compass data are lost magnetic field strength is about 0xEA6 lsb due to cancelling of low byte most of this data are lost. details https://github.com/iNavFlight/inav/issues/10746
2. Due to n.1 seems that no one use RM3100 compass with Inav. SPI is rarely accessible on most FC, so it is logical to change the bus to I2C and possible somebody will use it. details https://github.com/iNavFlight/inav/issues/10747
3. The order or initializing registers is incorrect. details https://github.com/iNavFlight/inav/issues/10748
4. A check new reading is unnecessary waste of time because sampling rate of compass is much more than reading rate. details https://github.com/iNavFlight/inav/issues/10752
5. Sampling rate can be substantially lower than default, used by Inav. This can lower the noise. details https://github.com/iNavFlight/inav/issues/10752

[b14ckyy]

Thanks a lot :)

[sensei-hacker]

It looks like you may have some good changes here. It also looks like indeed you're almost the only one using it, other than that old Matek board. Want to make a pull request or two?

[and-sh]

Sorry for delay, very busy due to work. I'll do it. Just explain the procedure in general. I'll figure it out from there. So far, I've only used GitHub for storing backups.