Channel 5 RF_TXCTRL should be updated to match latest value defined in DW1000 UM

[seppestas]

Originally reported on the Decawave forum

Version >=v2.16 of the DW1000 user manual defines RF_TXCTRL should be set to 0x001E3FE3 for UWB channel 5. Using the old value (0x001E3FE0) can result in ~2dB spurs in the channel 5 TX spectrum.

Please update the decadriver to the latest version of the DW1000 API or at least update this value since it can cause regulatory issues when using channel 5, meaning a lower TX power has to be used to meet regulation.