iio: light: fix improper return value

In function cm3232_reg_init(), it returns 0 even if the last call to
i2c_smbus_write_byte_data() returns a negative value (indicates error).
As a result, the return value may be inconsistent with the execution
status, and the caller of cm3232_reg_init() will not be able to detect
the error. This patch fixes the bug.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188641

Signed-off-by: Pan Bian <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/light/cm3232.c

···
 	if (ret < 0)
 		dev_err(&chip->client->dev, "Error writing reg_cmd\n");
 
-	return 0;
+	return ret;
 }
 
 /**