net: pcs: xpcs: Add support for FBNIC 25G, 50G, 100G PMD

net: pcs: xpcs: Add support for FBNIC 25G, 50G, 100G PMD

The fbnic driver is planning to make use of the XPCS driver to enable
support for PCS and better integration with phylink. To do this though we
will need to enable several workarounds since the PMD interface for fbnic
is likely to be unique since it is a mix of two different vendor products
with a unique wrapper around the IP.

I have generated a PHY identifier based on IEEE 802.3-2022 22.2.4.3.1 using
an OUI belonging to Meta Platforms and used with our NICs. Using this we
will provide it as the PMD ID via the SW based MDIO interface so that
the fbnic device can be identified and necessary workarounds enabled in the
XPCS driver.

As an initial workaround this change adds an exception so that soft_reset
is not set when the driver is initially bound to the PCS.

In addition I have added logic to integrate the PMD Rx signal detect state
into the link state for the PCS. With this we can avoid the link coming up
too soon on the FBNIC PMD and as a result of it being in the training state
so we can avoid link flaps.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://patch.msgid.link/176374321695.959489.6648161125012056619.stgit@ahduyck-xeon-server.home.arpa
Signed-off-by: Paolo Abeni <pabeni@redhat.com>