octeontx2-af: Support to modify min/max allowed packet lengths

This patch adds support for RVU PF/VFs to modify min/max
packet lengths allowed by HW. For VFs on PF0, settings will
be automatically applied on LBK link. RX link's min/maxlen
is configured to min/max of PF and it's all VFs. On the TX side
if requested all SMQs attached to the requesting NIXLF will be
updated with new min/max lengths.

Also updates transmit credits for Tx links based on new maxlen.

Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>