mmc: block: fix logical error to avoid memory leak

If the MMC_DRV_OP_GET_EXT_CSD request completes successfully, then
ext_csd must be freed, but in one case it was not. Fix that.

Signed-off-by: Liu Changcheng <changcheng.liu@intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/block.c

@@ -2795,6 +2795,7 @@ static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 
 	if (n != EXT_CSD_STR_LEN) {
 		err = -EINVAL;
+		kfree(ext_csd);
 		goto out_free;
 	}