iwlwifi: initialize spinlock before use

Recent powersaving work resulted in power management ops being called
during EEPROM initialization. The lock used by these functions is not
initialized at this time. Ensure lock is initialized before it is used.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>