Convert CONFIG_CMD_TCA642X to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_TCA642X

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/omap5_uevm_defconfig b/configs/omap5_uevm_defconfig
index c613433..273be58 100644
--- a/configs/omap5_uevm_defconfig
+++ b/configs/omap5_uevm_defconfig
@@ -36,6 +36,7 @@
 CONFIG_ISO_PARTITION=y
 CONFIG_DFU_MMC=y
 CONFIG_DFU_RAM=y
+CONFIG_CMD_TCA642X=y
 CONFIG_MMC_OMAP_HS=y
 CONFIG_SCSI=y
 CONFIG_SYS_NS16550=y