staging: fsl-dpaa2/eth: Remove Rx frame size check

Most Ethernet drivers don't enforce the MTU value as upper limit
for ingress frames. We too support receiving frames larger than
MTU, so allow that.

Remove our ndo_change_mtu implementation, letting the default
stack implementation handle things. Also, set the max frame length
allowed by hardware only once at probe time, with the largest
possible value.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>