mmc: block: make function mmc_cqe_issue_type static

The function mmc_cqe_issue_type is local to the source and does
not need to be in global scope, so make it static.

Cleans up sparse warning:
drivers/mmc/core/queue.c:62:21: warning: symbol 'mmc_cqe_issue_type'
was not declared. Should it be static?
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/queue.c

@@ -59,7 +59,7 @@ static inline bool mmc_cqe_can_dcmd(struct mmc_host *host)
 	return host->caps2 & MMC_CAP2_CQE_DCMD;
 }
 
-enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
+static enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
 					      struct request *req)
 {
 	switch (req_op(req)) {