net/failsafe: report minimum and maximum MTU
net/failsafe: report minimum and maximum MTU

Take minimum and maximum MTU values for subdevices and
report maximum of minimums and minimum of maximums.

Fixes: ad97ceece12c ("ethdev: add min/max MTU to device info")
Cc: stable@dpdk.org

Signed-off-by: Andrew Rybchenko <4155e7bf8e0185127625dac6d84336299844982f@oktetlabs.ru>
Acked-by: Gaetan Rivet <5349a78fb7b717c3a3b30d04e535485ef35093c6@u256.net>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk