Convert CONFIG_SYS_CONSOLE_IS_IN_ENV and CONFIG_CONSOLE_MUX to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_CONSOLE_IS_IN_ENV
   CONFIG_CONSOLE_MUX

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Re-order, re-migrate]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/cm_t335_defconfig b/configs/cm_t335_defconfig
index f135353..075829f 100644
--- a/configs/cm_t335_defconfig
+++ b/configs/cm_t335_defconfig
@@ -1,6 +1,5 @@
 CONFIG_ARM=y
 CONFIG_AM33XX=y
-CONFIG_TARGET_CM_T335=y
 CONFIG_SPL_GPIO_SUPPORT=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
@@ -12,6 +11,7 @@
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_SPL_POWER_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_TARGET_CM_T335=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_VERSION_VARIABLE=y
 CONFIG_SPL=y