Add BMA421 driver and small accelerometer module

[sdorre]

• BMA421 simple driver feature only 3-axis data provided by interrupt
• accelerometer module fetch these data and log it to the debug output

Signed-off-by: Stephane Dorre [email protected]

• [ ] Add Basic movement detection
• [ ] Rewrite driver to remove BSD-3 clause from Bosch SensorTech and make it lighter
• [ ] Add Power Management feature & disable accelerometer if needed (PWR_CTRL.acc_en = 0b0)

[endian-albin]

Sorry, @sdorre, I didn't see this is a draft. I'll let you continue working in peace.