Revert "mb/aopen/dxplplusu: Remove board"

This reverts commit eb76a455cd
and applies minor fixes to make it build again.

PARALLEL_MP was working prior to board removal and no
relevant SMI handlers were implemented. So NO_SMM choice
is now selected.

Change-Id: Ia1cd02278240d1b5d006fb2a7730d3d86390f85b
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69339
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/arch/x86/smbios.c

@@ -382,6 +382,8 @@ static int get_socket_type(void)
 {
 	if (CONFIG(CPU_INTEL_SLOT_1))
 		return 0x08;
+	if (CONFIG(CPU_INTEL_SOCKET_MPGA604))
+		return 0x13;
 	if (CONFIG(CPU_INTEL_SOCKET_LGA775))
 		return 0x15;
 	if (CONFIG(XEON_SP_COMMON_BASE))