mmc: core: Add claiming of hosts during mmc_cache_ctrl

While calling mmc_cache_ctrl() a host is not claimed. This patch
adds the mmc_try_claim_host() for quick response in suspend.

Signed-off-by: Seungwon Jeon <[e-mail]>
Signed-off-by: Chris Ball <[e-mail]>

drivers/mmc/core/core.c

···
 		cancel_delayed_work(&host->disable);
 	cancel_delayed_work(&host->detect);
 	mmc_flush_scheduled_work();
-	err = mmc_cache_ctrl(host, 0);
+	if (mmc_try_claim_host(host)) {
+		err = mmc_cache_ctrl(host, 0);
+		mmc_do_release_host(host);
+	} else {
+		err = -EBUSY;
+	}
+
 	if (err)
 		goto out;