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/P1020RDB-PD_SPIFLASH_defconfig b/configs/P1020RDB-PD_SPIFLASH_defconfig
index 02cbb69..65adc69 100644
--- a/configs/P1020RDB-PD_SPIFLASH_defconfig
+++ b/configs/P1020RDB-PD_SPIFLASH_defconfig
@@ -3,3 +3,4 @@
 CONFIG_TARGET_P1_P2_RDB_PC=y
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="P1020RDB_PD,SPIFLASH"
+CONFIG_CMD_SETEXPR=y