NRF_QSPI_NOR: Exit DPD mode regardless of CONFIG_PM_DEVICE.

A call to exit_dpd mode for the nrf QSPI nor flash should always be
made, even if the currently executing image is compiled with
CONFIG_PM_DEVICE=n, because a previously executing image could have set
the device into DPD mode, and a call to exit_dpd is required for proper
functionality. Call `exit_dpd` regardless of the setting of
CONFIG_PM_DEVICE during QSPI nor initialization.

Signed-off-by: Nickolas Lapp <nickolaslapp@gmail.com>