mmc: tmio, renesas_sdhi: Remove unneeded NULL check

The inconsistent NULL checking in this function causes static checker
warnings.

    drivers/mmc/host/renesas_sdhi_sys_dmac.c:360 renesas_sdhi_sys_dmac_issue_tasklet_fn()
    error: we previously assumed 'host' could be null (see line 351)

On reviewing this code, "host" can't ever be NULL so we can just remove
the check.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/renesas_sdhi_sys_dmac.c

@@ -348,7 +348,7 @@ static void renesas_sdhi_sys_dmac_issue_tasklet_fn(unsigned long priv)
 
 	spin_lock_irq(&host->lock);
 
-	if (host && host->data) {
+	if (host->data) {
 		if (host->data->flags & MMC_DATA_READ)
 			chan = host->chan_rx;
 		else