iwlwifi: fix config variable name in comment

The correct variable name was replaced here by mistake by commit
ab27926d ("iwlwifi: fix devices with PCI Device ID 0x34F0 and 11ac RF
modules").

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Link: https://lore.kernel.org/r/20200210135817.31994-1-luca@lucaceresoli.net


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