soc/intel/tigerlake: Hook up S0ix setting to option API

Hook up the s0ix_enable setting to the option API, so it can be changed
at runtime without recompilation. Default to the value set by the
mainboard.

Change-Id: I6c05212eaf004ea74b7fd3fa92cbaa314474b7e9
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/87503
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>

src/soc/intel/tigerlake/fsp_params.c

@@ -682,6 +682,9 @@ void platform_fsp_silicon_init_params_cb(FSPS_UPD *supd)
 	params->SiSkipSsidProgramming = 0;
 
 	mainboard_silicon_init_params(params);
+
+	/* Runtime configuration of S0ix */
+	config->s0ix_enable = get_uint_option("s0ix_enable", config->s0ix_enable);
 }
 
 /*