Move setexpr to Kconfig

Another shell scripting command that has not been moved.

Moved using tools/moveconfig.py using these settings:

CMD_SETEXPR bool n y

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/km_kirkwood_128m16_defconfig b/configs/km_kirkwood_128m16_defconfig
index 6b69c6d..16d5f55 100644
--- a/configs/km_kirkwood_128m16_defconfig
+++ b/configs/km_kirkwood_128m16_defconfig
@@ -2,3 +2,4 @@
 CONFIG_KIRKWOOD=y
 CONFIG_TARGET_KM_KIRKWOOD=y
 CONFIG_SYS_EXTRA_OPTIONS="KM_KIRKWOOD_128M16"
+CONFIG_CMD_SETEXPR=y