octeontx2-pf: Reduce minimum mtu size to 60

octeontx2-pf: Reduce minimum mtu size to 60

PTP messages like SYNC, FOLLOW_UP, DELAY_REQ are of size 58 bytes.
Using a minimum packet length as 64 makes NIX to pad 6 bytes of
zeroes while transmission. This is causing latest ptp4l application to
emit errors since length in PTP header and received packet are not same.
Padding upto 3 bytes is fine but more than that makes ptp4l to assume
the pad bytes as a TLV. Hence reduce the size to 60 from 64.

Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Link: https://lore.kernel.org/r/20220729092457.3850-1-naveenm@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>