Merge branch 'net-stmmac-dwmac-enforce-preamble-before-sfd-for-i-mx8mp'

Stefan Eichenberger says:

====================
net: stmmac: dwmac: enforce preamble before SFD for i.MX8MP

This series adds a new phy_device flag PHY_F_KEEP_PREAMBLE_BEFORE_SFD
that allows a MAC driver to request to keep the preamble bytes before
the start frame delimiter (SFD) when receiving frames from the PHY.

This flag is set in the stmmac driver for the i.MX8MP SoC due to errata
(ERR050694), which causes it to drop frames without a preamble.

The Micrel KSZ9131 PHY supports keeping the preamble before SFD by
setting an undocumented flag, that was confirmed by NXP and Micrel. This
new feature has been added to the Micrel PHY driver for the KSZ9131 PHY.
====================

Link: https://patch.msgid.link/20260120203905.23805-1-eichest@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>