Remove obsolete drivers wrappers: atmel, ndiswrapper, ipw, hermes

Remove obsolete drivers wrappers: atmel, ndiswrapper, ipw, hermes

There is no real reason to maintain these in the current development
branch anymore. If someone really needs support for the obsolete
driver interfaces, these can be found in older wpa_supplicant
branches.

driver_atmel.c
- vendor-specific interface for ATMEL AT76C5XXx cards
- for some old out-of-tree driver; not for the upstream atmel*
  drivers

driver_ndiswrapper.c
- vendor-specific interface for an out-of-tree driver
- ndiswrapper should work with driver_wext.c, too

driver_ipw.c
- vendor-specific interface for old ipw2100/2200 driver
- the upstream driver works with driver_wext.c (and does not work
  with the old interface)

driver_hermes.c
- vendor driver that was not even included in the main wpa_supplicant
  releases