adjust order of elements in ndo_printers[]

DLT_EN10MB, the most commonly seen datalink type, used to be the first
element of ndo_printers[], which lookup_ndo_printer() iterates over, but
commit 20ad836 made DLT_NFLOG the first. Move DLT_NFLOG to the last
position to make the function spend the same time processing the
previously recognized datalink types as before.