drivers: flash: nrf_qspi_nor: Process ret of qspi_device_init

Commit slters z_impl_nrf_qspi_nor_xip_enable to not call
qspi_device_init in case when xip_enabled has the same value
as requested.
In case when qspi_device_init returns non-zero no further actions
are taken and xip_enabled will not be to set requested value.

Fixes #59535.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>