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/trats2_defconfig b/configs/trats2_defconfig
index 59b73ca..e226abf 100644
--- a/configs/trats2_defconfig
+++ b/configs/trats2_defconfig
@@ -6,6 +6,7 @@
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
+CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="Trats2 # "
 CONFIG_CMD_BOOTZ=y