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/T2080RDB_SPIFLASH_defconfig b/configs/T2080RDB_SPIFLASH_defconfig
index 0dce597..87c8093 100644
--- a/configs/T2080RDB_SPIFLASH_defconfig
+++ b/configs/T2080RDB_SPIFLASH_defconfig
@@ -3,3 +3,4 @@
 CONFIG_TARGET_T208XRDB=y
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T2080,RAMBOOT_PBL,SPL_FSL_PBL,SPIFLASH"
+CONFIG_CMD_SETEXPR=y