- remove em_adapter_list, it was not used for anything beside adding and

- remove em_adapter_list, it was not used for anything beside adding and
  removing entries
- fix const warning for em_strings
- convert u_intXX_t to uintXX_t
- style(9) changes for whitespace e.g. consistent use of tabs
- use snprintf to build the adapter version string, we are embedding a
  string which could grow in size
- remove check for device_get_softc(dev) == NULL, this must not happen
- prefer device_printf and if_printf over printf("em0d: ...", addapter->unit)
- make some pointer checks explicit against NULL
- remove some of the #ifdef FreeBSD cases which are not interesting for us
- remove trailing return; in void functions
- use the pci accessor functions for the subsystem id and vendor
- start using bus_alloc_resource_any
- remove em_read_reg_io, em_write_reg_io, em_io_read and em_io_write,
  those are unused and doesn't fit into our newbus scheme.