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/goflexhome_defconfig b/configs/goflexhome_defconfig
index 8eeeafb..46527e5 100644
--- a/configs/goflexhome_defconfig
+++ b/configs/goflexhome_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_GOFLEXHOME=y
 CONFIG_IDENT_STRING="\nSeagate GoFlex Home"
 CONFIG_BOOTDELAY=3
+CONFIG_CONSOLE_MUX=y
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_SYS_PROMPT="GoFlexHome> "
 # CONFIG_CMD_IMLS is not set