blk: Use a macro for the typical block size

Avoid using the magic number 512 directly.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/block/blkmap.c b/drivers/block/blkmap.c
index 2bb0acc..409aa46 100644
--- a/drivers/block/blkmap.c
+++ b/drivers/block/blkmap.c
@@ -390,7 +390,7 @@
 	int err;
 
 	err = blk_create_devicef(dev, "blkmap_blk", "blk", UCLASS_BLKMAP,
-				 dev_seq(dev), 512, 0, &bm->blk);
+				 dev_seq(dev), DEFAULT_BLKSZ, 0, &bm->blk);
 	if (err)
 		return log_msg_ret("blk", err);
 
diff --git a/drivers/block/host_dev.c b/drivers/block/host_dev.c
index 6442241..31c7814 100644
--- a/drivers/block/host_dev.c
+++ b/drivers/block/host_dev.c
@@ -105,7 +105,7 @@
 	int ret;
 
 	ret = blk_create_devicef(dev, "sandbox_host_blk", "blk", UCLASS_HOST,
-				 dev_seq(dev), 512, 0, &blk);
+				 dev_seq(dev), DEFAULT_BLKSZ, 0, &blk);
 	if (ret)
 		return log_msg_ret("blk", ret);