[PATCH 21/22] blk: Support iteration

[Simon Glass]

It is useful to be able to iterate over block devices. Typically there
are fixed and removable devices. For security reasons it is sometimes
useful to ignore removable devices since they are under user control.

Add iterators which support selecting the block-device type.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 drivers/block/blk-uclass.c | 49 +++++++++++++++++++++++++++++++++
 include/blk.h              | 56 ++++++++++++++++++++++++++++++++++++++
 test/dm/blk.c              | 55 +++++++++++++++++++++++++++++++++++++
 3 files changed, 160 insertions(+)

Applied to u-boot-dm, thanks!