igbvf: Replace spin_is_locked() with lockdep

lockdep_assert_held() is better suited to checking locking requirements,
since it won't get confused when someone else holds the lock. This is
also a step towards possibly removing spin_is_locked().
Signed-off-by: Lance Roy <ldr709@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igbvf/mbx.c

@@ -241,7 +241,7 @@ static s32 e1000_write_mbx_vf(struct e1000_hw *hw, u32 *msg, u16 size)
 	s32 err;
 	u16 i;
 
-	WARN_ON_ONCE(!spin_is_locked(&hw->mbx_lock));
+	lockdep_assert_held(&hw->mbx_lock);
 
 	/* lock the mailbox to prevent pf/vf race condition */
 	err = e1000_obtain_mbx_lock_vf(hw);
@@ -279,7 +279,7 @@ static s32 e1000_read_mbx_vf(struct e1000_hw *hw, u32 *msg, u16 size)
 	s32 err;
 	u16 i;
 
-	WARN_ON_ONCE(!spin_is_locked(&hw->mbx_lock));
+	lockdep_assert_held(&hw->mbx_lock);
 
 	/* lock the mailbox to prevent pf/vf race condition */
 	err = e1000_obtain_mbx_lock_vf(hw);