spi: cadence-quadspi: use macro DEFINE_SIMPLE_DEV_PM_OPS

spi: cadence-quadspi: use macro DEFINE_SIMPLE_DEV_PM_OPS

Using this macro makes the code more readable.
It also inits the members of dev_pm_ops in the following manner
without us explicitly needing to:

.suspend = cqspi_suspend, \
.resume = cqspi_resume, \
.freeze = cqspi_suspend, \
.thaw = cqspi_resume, \
.poweroff = cqspi_suspend, \
.restore = cqspi_resume

Also get rid of conditional compilation based on CONFIG_PM_SLEEP because
it introduces build issues with certain configs when CQSPI_DEV_PM_OPS is
just NULL.

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202304191900.2fARFQW9-lkp@intel.com/
Fixes: 140623410536 ("mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller")
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230420054257.925092-1-d-gole@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>