boards/feather-m0: sx127x params only valid for lora vairiant
boards/feather-m0: sx127x params only valid for lora vairiant

In the feather-m0 board the sx127x pin parameters are hardcoded for the
feather-m0-lora variant, but this is not compatible with other
configurations.

For example in the feather-m0 adalogger PA06 and PA08 are used for the
SD card. When combined with the RFM95W FeatherWing the IRQ/CS/RST pins
must be wired, and then the sx127x pins must be configured to match the
wiring (which will be necessarily different from the lora variant
configuration).

RIOT-OS/RIOT,miri64/RIOT,OlegHahm/RIOT,jasonatran/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,OlegHahm/RIOT,kaspar030/RIOT,miri64/RIOT,jasonatran/RIOT,ant9000/RIOT,RIOT-OS/RIOT,ant9000/RIOT,OlegHahm/RIOT,kYc0o/RIOT,kaspar030/RIOT,ant9000/RIOT,kaspar030/RIOT,kYc0o/RIOT,kaspar030/RIOT,miri64/RIOT,ant9000/RIOT,miri64/RIOT,kaspar030/RIOT,OlegHahm/RIOT,kYc0o/RIOT,OlegHahm/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,miri64/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,jasonatran/RIOT,ant9000/RIOT