soc/amd/picasso: solve MTRRs only from 4GiB and below

Use x86_setup_mtrrs_with_detect_no_above_4gb() to only
solve the MTRR solution for memory up to 4GiB. This assumes
4GiB to TOM2 is marked as writeback in sys_cfg MSR.

BUG=b:155426691

Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Change-Id: Ib8358b614682f6a97278f3a60b5ada5e607965af
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41898
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/picasso/cpu.c

@@ -36,7 +36,7 @@ static struct smm_relocation_params smm_reloc_params;
  */
 static void pre_mp_init(void)
 {
-	x86_setup_mtrrs_with_detect();
+	x86_setup_mtrrs_with_detect_no_above_4gb();
 	x86_mtrr_check();
 }