Convert CONFIG_CMD_EECONFIG to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_EECONFIG

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/gwventana_gw5904_defconfig b/configs/gwventana_gw5904_defconfig
index 0aef36a..49566ce 100644
--- a/configs/gwventana_gw5904_defconfig
+++ b/configs/gwventana_gw5904_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_TARGET_GW_VENTANA=y
+CONFIG_CMD_EECONFIG=y
 CONFIG_SPL_MMC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y