drm/panfrost: devfreq: Don't display error for EPROBE_DEFER

Set a condition for the message of "Couldn't set OPP regulators" to not
display if the error code is EPROBE_DEFER. Note that I used an if
statement to capture the condition instead of the dev_err_probe
function because I didn't want to change the DRM_DEV_ERROR usage.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210721214830.25690-1-macroalpha82@gmail.com

drivers/gpu/drm/panfrost/panfrost_devfreq.c

@@ -106,6 +106,7 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
 	if (ret) {
 		/* Continue if the optional regulator is missing */
 		if (ret != -ENODEV) {
+			if (ret != -EPROBE_DEFER)
 				DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
 			return ret;
 		}