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/MIP405_defconfig b/configs/MIP405_defconfig
index 779759e..9c77df8 100644
--- a/configs/MIP405_defconfig
+++ b/configs/MIP405_defconfig
@@ -4,6 +4,8 @@
 CONFIG_4xx=y
 CONFIG_TARGET_MIP405=y
 CONFIG_BOOTDELAY=5
+# CONFIG_CONSOLE_MUX is not set
+CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_I2C=y