Convert CONFIG_CMD_CHIP_CONFIG to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_CHIP_CONFIG

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sequoia_ramboot_defconfig b/configs/sequoia_ramboot_defconfig
index 3214d45..ddafa27 100644
--- a/configs/sequoia_ramboot_defconfig
+++ b/configs/sequoia_ramboot_defconfig
@@ -1,6 +1,7 @@
 CONFIG_PPC=y
 CONFIG_4xx=y
 CONFIG_TARGET_SEQUOIA=y
+CONFIG_CMD_CHIP_CONFIG=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_SYS_EXTRA_OPTIONS="SEQUOIA,SYS_RAMBOOT,SYS_TEXT_BASE=0x01000000,SYS_LDSCRIPT=board/amcc/sequoia/u-boot-ram.lds"
 CONFIG_BOOTDELAY=5