iwlwifi: Add eeprom version to the version file in sysfs

This patch adds eeprom version display into device/version sysfs file
/sys/class/net/wlanX/devices/version

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>