Declare recovery and developer modes outside ChromeOS

Move the implementation for recovery and developer modes from
vendorcode/google/chromes to lib/.

Change-Id: I33335fb282de2c7bc613dc58d6912c47f3b5c06c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/4308
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/Kconfig

@@ -300,6 +300,10 @@ config MMCONF_SUPPORT
 	bool
 	default n
 
+config BOOTMODE_STRAPS
+	bool
+	default n
+
 source src/console/Kconfig
 
 config HAVE_ACPI_RESUME