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/efi-x86_defconfig b/configs/efi-x86_defconfig
index eb55e93..c47f314 100644
--- a/configs/efi-x86_defconfig
+++ b/configs/efi-x86_defconfig
@@ -3,6 +3,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="efi"
 CONFIG_TARGET_EFI=y
 CONFIG_FIT=y
+CONFIG_CONSOLE_MUX=y
 CONFIG_HUSH_PARSER=y
 # CONFIG_CMD_BOOTM is not set
 # CONFIG_CMD_IMLS is not set