drivers: flash: nrf_qspi: cleanup JEDEC ID length
drivers: flash: nrf_qspi: cleanup JEDEC ID length

QSPI doesn't have a different length expectation than normal SPI, so
introducing a new name for an existing name is unnecessary.  Also
replace the constant with the actual buffer size where appropriate, in
somebody changes the the buffer definition.

Signed-off-by: Peter Bigot <a4112a160b558d5427af084318038e19a95979ee@nordicsemi.no>

nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr