iwlwifi: rename GEO_TX_POWER_LIMIT to PER_CHAIN_LIMIT_OFFSET_CMD

When this code was implemented, there was no official FW API
description yet, so a placeholder name was used (GEO_TX_POWER_LIMIT).
But then the command became actually called
PER_CHAIN_LIMIT_OFFSET_CMD.  Rename the command (and change related
comments) to PER_CHAIN_LIMIT_OFFSET_CMD to avoid confusion.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211024181719.672fa727ef75.I6572df5d1e3441a0214993a59985da9a9431f3e5@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>