exynos: config: enable setexpr command for smdk5250 based boards

This adds the setexpr command which allows basic evaluations in hex, which
is useful for some U-boot command scripts involving addresses.

BUG=chromium:242757
TEST=Manual, boot up U-Boot image, verify setexpr command is in help and
functions.
BRANCH=none

Change-Id: I33158e7588d2c1e98a5bfc2cd8d074e0a751eae8
Signed-off-by: Bernie Thompson <bhthompson@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56609
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed