nrf_drv_spi NRF_LOG_HEXDUMP_DEBUG too long

[Nicolas Brunner]

The NRF_LOG_HEXDUMP_DEBUG for rx and tx in nrf_drv_spi.c are logging data 4x the correct size because it take the sizeof of a pointer instead of the data pointed.

[Jørgen Holmefjord]

Thanks for reporting this. I have reported the issue internally.