mb/siemens/mc_ehl: Enable Row-Hammer prevention

As a prevention of Row-Hammer attacks enable the FSP-M parameter
'RhPrevention'.

Change-Id: I52f68525e882aee26822d9b3c488639c00f27d17
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58856
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

src/mainboard/siemens/mc_ehl/romstage_fsp_params.c

@@ -33,4 +33,7 @@ void mainboard_memory_init_params(FSPM_UPD *memupd)
 	}
 	/* Initialize variant specific configurations */
 	memcfg_init(&memupd->FspmConfig, board_cfg, &spd_info, false);
+
+	/* Enable Row-Hammer prevention */
+	memupd->FspmConfig.RhPrevention = 1;
 }