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/B4860QDS_SECURE_BOOT_defconfig b/configs/B4860QDS_SECURE_BOOT_defconfig
index c2e9acc..9e1f1c4 100644
--- a/configs/B4860QDS_SECURE_BOOT_defconfig
+++ b/configs/B4860QDS_SECURE_BOOT_defconfig
@@ -2,3 +2,4 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_B4860QDS=y
 CONFIG_SYS_EXTRA_OPTIONS="PPC_B4860,SECURE_BOOT"
+CONFIG_CMD_SETEXPR=y