iwlwifi: don't read sku information from EEPROM for 4965

For all the new devices, the sku information should read from EEPROM
but for legacy devices such as 4965, appearly the EEPROM does not
contain the necessary information. so skip the read from EEPROM
and go back to use software configuration.

Reported-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Tested-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>