iwlwifi: mvm: remove redundant d0i3 flag from the config struct

The d0i3 flag in the device configuration structure is redundant,
because the same information can be determined by checking the
firmware capability flag.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>