Make sure functions calling rtl838x_smi_wait_op() return its return
value in target/linux/realtek/files-5.15/drivers/net/dsa/rtl83xx/rtl838x.c.
This brings the code style in line with the rtl839x implementation.
Suggested-by: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Pascal Ernster <git@hardfalcon.net>