Merge branch 'mlxsw-Derive-SBIB-from-maximum-port-speed-and-MTU'

Ido Schimmel says:

====================
mlxsw: Derive SBIB from maximum port speed & MTU

Petr says:

Internal buffer is a part of port headroom used for packets that are
mirrored due to triggers that the Spectrum ASIC considers "egress". Besides
ACL mirroring on port egresss this includes also packets mirrored due to
ECN marking.

This patchset changes the way the internal mirroring buffer is reserved.
Currently the buffer reflects port MTU and speed accurately. In the future,
mlxsw should support dcbnl_setbuffer hook to allow the users to set buffer
sizes by hand. In that case, there might not be enough space for growth of
the internal mirroring buffer due to MTU and speed changes. While vetoing
MTU changes would be merely confusing, port speed changes cannot be vetoed,
and such change would simply lead to issues in packet mirroring.

For these reasons, with these patches the internal mirroring buffer is
derived from maximum MTU and maximum speed achievable on the port.

Patches #1 and #2 introduce a new callback to determine the maximum speed a
given port can achieve.

With patches #3 and #4, the information about, respectively, maximum MTU
and maximum port speed, is kept in struct mlxsw_sp_port.

In patch #5, maximum MTU and maximum speed are used to determine the size
of the internal buffer. MTU update and speed update hooks are dropped,
because they are no longer necessary.
====================

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