lsm6ds3tr: avoid unnecessary heap allocations

[ysoldak]

This re-uses internal buffer to avoid unnecessary heap allocations in lsm6ds3tr driver; switches away from the legacy I2C interface.

[soypat]

Nit that I think would do wonders for readability. I'd love to feature this in a youtube video once it is done if y'all don't mind!

[soypat]

Could we abstract these calls to something like d.writeReg8/readReg8 ?

func (d *Device) writeReg8(addr, value byte) error {
   d.buf[0] = addr
   d.buf[1] = value
   return err = d.bus.Tx(d.Address, d.buf[0:2], nil)
}

func (d *Device) readReg8(addr byte) (byte,error) {
   d.buf[0] = addr
   err := d.bus.Tx(d.Address, d.buf[0:1], d.buf[1:2])
   return d.buf[1], err
}

[ysoldak]

This is just one of many drivers that scream for such improvement, a trial balloon if you wish.
Each of these drivers will have to repeat the pattern.

Any ideas how could we implement these helper functions once and re-use them, instead of implementing in every driver anew?

[aykevl]

LGTM, but I agree with @soypat some helper methods would make the code a bit easier to read.

[ysoldak]

Nit that I think would do wonders for readability. I'd love to feature this in a youtube video once it is done if y'all don't mind!

Nothing against from my side. All kudos to @aykevl for the idea, btw.