net: cadence: macb: Synchronize standard stats

The new stats calculations add several additional calls to
macb/gem_update_stats() and accesses to bp->hw_stats. These are
protected by a spinlock since commit fa52f15c ("net: cadence: macb:
Synchronize stats calculations"), which was applied in parallel. Add
some locking now that the net has been merged into net-next.

Fixes: f6af690a ("net: cadence: macb: Report standard stats")
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Link: https://patch.msgid.link/20250303231832.1648274-1-sean.anderson@linux.dev


Signed-off-by: Jakub Kicinski <kuba@kernel.org>