RX delay and TX delay can be configured independently on the RTL8211F.
Decode the phy mode setting and set both bits accordingly. This is based
on Linux commit 1b3047b5208a ("net: phy: realtek: add support for
configuring the RX delay on RTL8211F")

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>