[U-Boot] [PATCH 23/25] test: sf: Add a simple SPI flash test

[sjg at google.com]

The current test is a functional test, covering all the way from the
command line to the sandbox SPI driver. This is useful, but it is easier
to diagnose failures with a smaller test.

Add a simple test which reads and writes data and checks that it is stored
and retrieved correctly.

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

 test/dm/sf.c | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

Applied to u-boot-dm/master, thanks!