net: enetc: convert mailbox messages to new formats

net: enetc: convert mailbox messages to new formats

On the LS1028A platform, the PF-VF mailbox was only used to update the
VF's MAC address. The original message format is minimal, lacks a clear
structure, and provides no means for the receiver to validate message
integrity, making it difficult to extend for new features.

With the introduction of i.MX ENETC v4, the interaction between PF and
VF has become significantly more complex. Typical deployments now include
scenarios where the PF is controlled by an M core while the VF is driven
by either the Linux kernel or DPDK, or where the PF is controlled by the
Linux kernel while the VF is controlled by DPDK. These heterogeneous
driver combinations require a unified and extensible message format to
ensure compatibility across different operating environments.

This patch introduces a newly defined PF-VF message structure and
converts the existing MAC-update mechanism to use the new format. The
redesigned message layout provides:

  - extensibility to support future PF-VF features on ENETC v4,
  - consistent framing for all message types,
  - improved data integrity checking,
  - a common protocol usable across Linux, M core firmware, and DPDK.

Additional PF-VF message types will be added in subsequent patches.

Note that switch to the new message format will not affect ENETC v1
(LS1028A). Due to a hardware limitation of ENETC v1, the ENETC PF and
VFs can only be controlled by the same OS. If the PF is controlled by
the Linux kernel driver, then the VFs must also be controlled by the
Linux kernel driver.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20260522092438.1264020-7-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>