selfboot: Move x86 quirk under arch

Making exceptions for some payload to be loaded near
and under 1 MiB boundary sounds like a legacy 16-bit
x86 BIOS thing we generally do not want under lib/.

Change-Id: I8e8336a03d6f06d8f022c880a8334fe19a777f0a
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/26934
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/arch/x86/boot.c

@@ -11,6 +11,7 @@
  * GNU General Public License for more details.
  */
 
+#include <commonlib/helpers.h>
 #include <console/console.h>
 #include <arch/stages.h>
 #include <program_loading.h>
@@ -205,6 +206,17 @@ int arch_supports_bounce_buffer(void)
 	return 1;
 }
 
+int payload_arch_usable_ram_quirk(uint64_t start, uint64_t size)
+{
+	if (start < 1 * MiB && (start + size) <= 1 * MiB) {
+		printk(BIOS_DEBUG,
+			"Payload being loaded at below 1MiB without region being marked as RAM usable.\n");
+		return 1;
+	}
+
+	return 0;
+}
+
 static void try_payload(struct prog *prog)
 {
 	if (prog_type(prog) == PROG_PAYLOAD) {