We use to cache whether the MNG FW was enabled, how since this isn't
static we really need to verify with each check.  This patch makes that
change.

CC: Arun Sharma <asharma@fb.com>
Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>