mmc: core: Add mmc_retune_hold_now()

mmc_return_hold() / mmc_retune_release() are used around a group of
commands to prevent re-tuning between the commands. Re-tuning can still
happen before the first command. In some cases, re-tuning must be
prevented entirely. Add mmc_retune_hold_now() for that purpose. It is
added in preparation for CQE support where it will be used by CQE recovery.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
index fb6a76a..77d6f60 100644
--- a/drivers/mmc/core/host.h
+++ b/drivers/mmc/core/host.h
@@ -19,6 +19,7 @@
 void mmc_retune_enable(struct mmc_host *host);
 void mmc_retune_disable(struct mmc_host *host);
 void mmc_retune_hold(struct mmc_host *host);
+void mmc_retune_hold_now(struct mmc_host *host);
 void mmc_retune_release(struct mmc_host *host);
 int mmc_retune(struct mmc_host *host);
 void mmc_retune_pause(struct mmc_host *host);