The lowest possible value is `LORA_SF5` and not `LORA_SF6`. This fixes
the argument validation to allow setting `LORA_SF5` as spreading factor.
Fixes https://github.com/RIOT-OS/RIOT/issues/17861
The RSSI values reported by LoRa transceiver can be less than -127.
Therefore, `int8_t` is not enough. This commit defines the RSSI of
`netdev_lora_rx_info` as `int16_t` and adapt the drivers accordingly
(sx126x, sx127x).
BOARDs with RF switch might only support one of the TX modes, and
on init the BOARD needs to be configured accordingly and the correct
mode selected on TX.
This commit fixes the send function of sx126x. The loop that reads the
iolist was not considering the offset. Therefore each iolist snippet was
being written into the first position.
The loop was also setting the payload length to the size of the iolist
snippet. Then the payload was also wrong.
With this commit an iolist is copied sequentially into the framebuffer
and the payload length is set to `iolist_size`
