dm: block: Rename device number member dev to devnum

This is a device number, and we want to use 'dev' to mean a driver model
device. Rename the member.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 8586d89..ef7e615 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -137,7 +137,7 @@
 	int trans_bytes = 0, is_aligned = 1;
 	u32 mask, flags, mode;
 	unsigned int time = 0, start_addr = 0;
-	int mmc_dev = mmc->block_dev.dev;
+	int mmc_dev = mmc->block_dev.devnum;
 	unsigned start = get_timer(0);
 
 	/* Timeout unit - ms */