Revert "Ethernet: Remove two useless tests"

Revert "Ethernet: Remove two useless tests"

This reverts commit b7fff7058282c332ba1d8d236c9864ab21b16adf (partially)

The sanity check in print.c/pretty_print_packet() function, packet length
(length) >= capture length (caplen), apply when the ether_print()
function is called by ether_if_print(), netanalyzer_if_print() or
netanalyzer_transparent_if_print().

But the ether_print() function is called in some other cases, thus not
sure length always >= caplen.