sfc: add missing annotation for efx_ef10_try_update_nic_stats_vf()

Sparse reports a warning at efx_ef10_try_update_nic_stats_vf()
warning: context imbalance in efx_ef10_try_update_nic_stats_vf()
	- unexpected unlock
The root cause is the missing annotation at
efx_ef10_try_update_nic_stats_vf()
Add the missing _must_hold(&efx->stats_lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/ef10.c

@@ -1819,6 +1819,7 @@ static size_t efx_ef10_update_stats_pf(struct efx_nic *efx, u64 *full_stats,
 }
 
 static int efx_ef10_try_update_nic_stats_vf(struct efx_nic *efx)
+	__must_hold(&efx->stats_lock)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_MAC_STATS_IN_LEN);
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;