cmd: Add 2048 game

Add the 2048 game, a good demo of ANSI sequences and a way to waste a
little time.

Bring it it from Barebox, modified for code style.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 3a1f14c..ca95b2c 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -340,3 +340,4 @@
 CONFIG_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+CONFIG_CMD_2048=y