sfc: remove set but not used variable 'nic_data'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/sfc/mcdi_functions.c: In function 'efx_mcdi_ev_init':
drivers/net/ethernet/sfc/mcdi_functions.c:79:28: warning:
 variable 'nic_data' set but not used [-Wunused-but-set-variable]

commit 4438b587 ("sfc: move MCDI event queue management code")
introduces this unused variable.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/mcdi_functions.c

@@ -76,13 +76,10 @@ int efx_mcdi_ev_init(struct efx_channel *channel, bool v1_cut_thru, bool v2)
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_INIT_EVQ_V2_OUT_LEN);
 	size_t entries = channel->eventq.buf.len / EFX_BUF_SIZE;
 	struct efx_nic *efx = channel->efx;
-	struct efx_ef10_nic_data *nic_data;
 	size_t inlen, outlen;
 	dma_addr_t dma_addr;
 	int rc, i;
 
-	nic_data = efx->nic_data;
-
 	/* Fill event queue with all ones (i.e. empty events) */
 	memset(channel->eventq.buf.addr, 0xff, channel->eventq.buf.len);