iwlagn: move nvm_device_type from iwl_priv to iwl_trans

The nvm_device_type is eeprom related and does not need to be part
of the iwl_priv structure.  Move it and eliminate access to the iwl_priv
structure.

Signed-off-by: Don Fry <donald.h.fry@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>