drivers: flash: remove usage of device_pm_control_nop

device_pm_control_nop is now deprecated in favour of NULL.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
diff --git a/drivers/flash/soc_flash_lpc.c b/drivers/flash/soc_flash_lpc.c
index e3fc213..be724bb 100644
--- a/drivers/flash/soc_flash_lpc.c
+++ b/drivers/flash/soc_flash_lpc.c
@@ -170,6 +170,6 @@
 	return 0;
 }
 
-DEVICE_DT_INST_DEFINE(0, flash_lpc_init, device_pm_control_nop,
+DEVICE_DT_INST_DEFINE(0, flash_lpc_init, NULL,
 			&flash_data, NULL, POST_KERNEL,
 			CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &flash_lpc_api);