Add the "askenv" command into the develper u-boot.

This will be useful for doing some basic scripting in u-boot for
factory bringup.

BUG=chrome-os-partner:3921
TEST=Built u-boot and used askenv command.

Change-Id: Ifab2d39b291c1d20736b404ed44d622843ea7d93
Reviewed-on: http://gerrit.chromium.org/gerrit/1091
Tested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
1 file changed