The MRF24J40MC/MD/ME modules contain an external power amplifier &
low noise amplifier that has to be enabled manually by setting three bits
in the TESTMODE register.
On MRF24J40MC the power amplifier is powered by a separate voltage regualtor
that has to be enabled by setting GPIO3 to HIGH.
During Sleep and CCA the PA should be disabled.
Co-authored-by: Carton <joel.carron@eeproperty.ch>
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>