Unify all Intel gigabit drivers into a single iflib implementation.
Changes need to be made to build and use if_lem for the boards that need it. Also, we are going to install a symlink from if_em.ko to if_igb.ko such that users of modules don't get immediately hosed on an update if they aren't building the drivers into the kernel and are expecting loader.conf 'if_igb_load=YES' to work.
Address review comments:
- restore broken white space
- remove uneeded #ifdef KLD_MODULE
Add installation of symlink during installkernel so that loader.conf:if_igb_load=YES
still works for users who are currently using igb(4) as a module and don't have em(4)
loaded or built into their kernel.