The macro `ARDUINO_SPI_D11D12D13` is used to refer to the SPI bus
on the pins D11/D12/D13 on Arduino UNO compatible boards. For all
Nucleo64 boards this is `SPI_DEV(0)`, but for this board `SPI_DEV(0)`
is internally connected to the radio. Instead `SPI_DEV(1)` is connected
to the correct pins. This provides the macro explicitly in
`periph_conf.h`, which takes preference over the fallback in
`boards/common/nucleo64` when provided.
