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/T1024QDS_SECURE_BOOT_defconfig b/configs/T1024QDS_SECURE_BOOT_defconfig
index a58b6b5..0a6e0b7 100644
--- a/configs/T1024QDS_SECURE_BOOT_defconfig
+++ b/configs/T1024QDS_SECURE_BOOT_defconfig
@@ -10,6 +10,8 @@
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T1024,SECURE_BOOT"
 CONFIG_BOOTDELAY=10
 CONFIG_SILENT_CONSOLE=y
+# CONFIG_CONSOLE_MUX is not set
+CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_MMC=y