mmc: core: Add helper to see if a host can be retuned

This is in preparation for restoring saved tuning parameters
when resuming the TMIO driver.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

include/linux/mmc/host.h

@@ -546,6 +546,11 @@ static inline void mmc_retune_recheck(struct mmc_host *host)
 		host->retune_now = 1;
 }
 
+static inline bool mmc_can_retune(struct mmc_host *host)
+{
+	return host->can_retune == 1;
+}
+
 void mmc_retune_pause(struct mmc_host *host);
 void mmc_retune_unpause(struct mmc_host *host);