ixgbe: fix the FWSM.PT check in ixgbe_mng_present()

Bits other than FWSM.PT can be set in IXGBE_SWFW_MODE_MASK making the
previous check invalid.

Change the check for MNG present to be only based on FWSM.PT bit.
Signed-off-by: NEmil Tantilov <emil.s.tantilov@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_common.c

@@ -4100,8 +4100,8 @@ bool ixgbe_mng_present(struct ixgbe_hw *hw)
 		return false;
 
 	fwsm = IXGBE_READ_REG(hw, IXGBE_FWSM(hw));
-	fwsm &= IXGBE_FWSM_MODE_MASK;
-	return fwsm == IXGBE_FWSM_FW_MODE_PT;
+
+	return !!(fwsm & IXGBE_FWSM_FW_MODE_PT);
 }
 
 /**