iwlwifi: mvm: fix old-style declaration

There expect the 'static' keyword to come first in a
declaration, and we get warnings like this with "make W=1":

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c:427:1: warning:
 'static' is not at beginning of declaration [-Wold-style-declaration]
drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c:434:1: warning:
 'static' is not at beginning of declaration [-Wold-style-declaration]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>