examples/radio-scannable-broadcaster: Reorganize code & comments
examples/ll-broadcaster: Sanitize interval timeout
ll: Reorganize code in ll_advertise_start()
nrf51822/radio: Fix buffer overflow bug

The radio input buffer must be able to store a full packet with 39
octets. But the MAXLEN configuration of NRF_RADIO->PCNF1 register
stores the maximum length of PAYLOAD, which is 37 octets, and not
the full packet.
nrf51822/radio: Remove outdated/unnecessary comments
nrf51822/radio: Remove outdated comment
nrf51822/radio: Remove unnecessary crc variable