iwlwifi: fix FAT channel config for 5000 series

The test to find out if we have FAT channels do not consider that
the value of regulatory_bands for the 5000 series is larger than its
eeprom size. Using the eeprom size is strange in itself.

Use a new EEPROM_REGULATORY_BAND_NO_FAT to indicate no FAT support
and test for that explicitly.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Samuel Ortiz <samuel.ortiz@intel.com>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>