soc/intel/alderlake: Disable Intel TXT based on `INTEL_TXT` config

This patch makes the call into TXT lib in order to disable the TXT
if SoC user haven't selected the `INTEL_TXT` config. Disabling TXT
would be helpful to access VGA framebuffer prior calling into FSP-M.

TEST=Able to perform disable_txt and unlock memory which helped to
access VGA framebuffer prior calling into FSP-M.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I9dd7c5492a5f45eef0dd9e836cc2da1844c78919
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71575
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
diff --git a/src/soc/intel/alderlake/Kconfig b/src/soc/intel/alderlake/Kconfig
index 1b2f695..132e812 100644
--- a/src/soc/intel/alderlake/Kconfig
+++ b/src/soc/intel/alderlake/Kconfig
@@ -73,6 +73,7 @@
 	select INTEL_GMA_ACPI
 	select INTEL_GMA_ADD_VBT if RUN_FSP_GOP
 	select INTEL_GMA_OPREGION_2_1
+	select INTEL_TXT_LIB
 	select MRC_SETTINGS_PROTECT
 	select PARALLEL_MP_AP_WORK
 	select PLATFORM_USES_FSP2_2