Put the LINUX_SLL_P_ definitions back, and check for at least some of

Put the LINUX_SLL_P_ definitions back, and check for at least some of
them in "print-sll.c" - as a cooked-mode capture may be reading from
non-Ethernet, non-802.x devices, it may well see some
ETH_P_/LINUX_SLL_P_ types that don't mean "this is an 802.2 LLC frame".

We currently assume that the ETH_P_ values won't change in the kernel,
so we don't have to explicitly map them.