iwlwifi: move eeprom pointer from iwl_priv to iwl_shared

The eeprom image is a device level component, move from iwl_priv
to iwl_shared, with associated code changes.

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