power: reset: nvmem-reboot-mode: quiet some device deferrals

Some errors are being logged that are really due to deferrals,
which is confusing to users. Use dev_err_probe() to handle when to log
at error level versus debug. This also has the added bonuses of logging
to devices_deferred and printing the error value.

Signed-off-by: Andrew Halaney <[e-mail]>
Reviewed-by: Brian Masney <[e-mail]>
Tested-by: Brian Masney <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/reset/nvmem-reboot-mode.c

···
 
 	nvmem_rbm->cell = devm_nvmem_cell_get(&pdev->dev, "reboot-mode");
 	if (IS_ERR(nvmem_rbm->cell)) {
-		dev_err(&pdev->dev, "failed to get the nvmem cell reboot-mode\n");
-		return PTR_ERR(nvmem_rbm->cell);
+		return dev_err_probe(&pdev->dev, PTR_ERR(nvmem_rbm->cell),
+				     "failed to get the nvmem cell reboot-mode\n");
 	}
 
 	ret = devm_reboot_mode_register(&pdev->dev, &nvmem_rbm->reboot);