iwlwifi: eeprom: clean up macros

There are two versions of the same definitions, with and without
IWL_ prefix. Use the ones with IWL_ prefix, keeping the correct
comment (microseconds).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220204122220.2150362427bd.I47a47d0f795dc08361958833b8235ab5de75d154@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>