Merge branch 'RTL8211F-RGMII-RX-TX-delay-configuration-improvements'

Merge branch 'RTL8211F-RGMII-RX-TX-delay-configuration-improvements'

Martin Blumenstingl says:

====================
RTL8211F: RGMII RX/TX delay configuration improvements

In discussion with Andrew [0] we figured out that it would be best to
make the RX delay of the RTL8211F PHY configurable (just like the TX
delay is already configurable).

While here I took the opportunity to add some logging to the TX delay
configuration as well.

There is no public documentation for the RX and TX delay registers.
I received this information a while ago (and created this RfC patch
back then: [1]). Realtek gave me permission to take the information
from the datasheet extracts and phase them in my own words and publish
that (I am not allowed to publish the datasheet extracts).

I have tested these patches on two boards:
- Amlogic Meson8b Odroid-C1
- Amlogic GXM Khadas VIM2
Both still behave as before these changes (iperf3 speeds are the same
in both directions: RX and TX), which is expected because they are
currently using phy-mode = "rgmii" with the RX delay not being generated
by the PHY.

[0] https://patchwork.ozlabs.org/patch/1215313/
[1] https://patchwork.ozlabs.org/patch/843946/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>