Add Kconfig options to enable TSEG and set a size

Future CPUs will require TSEG use for SMM

Change-Id: I1432569ece4371d6e12c997e90d66c175fa54c5c
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: http://review.coreboot.org/766
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/x86/Kconfig

@@ -43,3 +43,11 @@ config LOGICAL_CPUS
 config CACHE_ROM
 	bool
 	default n
+
+config SMM_TSEG
+	bool
+	default n
+
+config SMM_TSEG_SIZE
+	hex
+	default 0