Add a helper function for this operation. Update the strtoul() tests to
check upper case as well.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
There are quite a few string functions in U-Boot with no tests. Make a
start by adding a test for strtoul().
Signed-off-by: Simon Glass <sjg@chromium.org>