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/T1040D4RDB_SECURE_BOOT_defconfig b/configs/T1040D4RDB_SECURE_BOOT_defconfig
index e437f3e..f548e21 100644
--- a/configs/T1040D4RDB_SECURE_BOOT_defconfig
+++ b/configs/T1040D4RDB_SECURE_BOOT_defconfig
@@ -9,6 +9,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T1040,T1040D4RDB,T104XD4RDB,SYS_FSL_DDR4,SECURE_BOOT"
 CONFIG_BOOTDELAY=10
 CONFIG_SILENT_CONSOLE=y
+CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_MMC=y