Bumping max frame size has significantly affected network performance.
It was done by upstream commit that first appeared in the 5.7 release.
This change bumps NAT masquarade speed from 196 Mb/s to 383 Mb/s for the
BCM4708 SoC.
Ref: f55f1dbaad ("bcm53xx: switch to the kernel 5.10")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
