sample/drivers/jesd216: spi-nor config for nrf52840dk

Added configuration which allows to test the sample using SPI_NOR
driver instead of NRF_QSPI driver.
SPI_NOR driver is generic, so nice to add possibility to check
how it is working.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>