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/MK808C_defconfig b/configs/MK808C_defconfig
index 88df54c..6b99d56 100644
--- a/configs/MK808C_defconfig
+++ b/configs/MK808C_defconfig
@@ -5,3 +5,4 @@
 CONFIG_DEFAULT_DEVICE_TREE="sun7i-a20-mk808c"
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,USB_EHCI"
+CONFIG_CMD_SETEXPR=y