Convert CONFIG_CMD_PCA953X to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_PCA953X

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/configs/cm_t335_defconfig b/configs/cm_t335_defconfig
index a88b2d8..1be7b36 100644
--- a/configs/cm_t335_defconfig
+++ b/configs/cm_t335_defconfig
@@ -45,6 +45,7 @@
 CONFIG_CMD_MTDPARTS=y
 CONFIG_ISO_PARTITION=y
 CONFIG_EFI_PARTITION=y
+CONFIG_CMD_PCA953X=y
 CONFIG_LED_STATUS=y
 CONFIG_LED_STATUS_GPIO=y
 CONFIG_LED_STATUS0=y