target/microblaze: Define TCG_GUEST_DEFAULT_MO

The microblaze architecture does not reorder instructions.
While there is an MBAR wait-for-data-access instruction,
this concerns synchronizing with DMA.

This should have been defined when enabling MTTCG.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar@zeroasic.com>
Fixes: d449561b130 ("configure: microblaze: Enable mttcg")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/microblaze/cpu.h

@@ -24,6 +24,9 @@
 #include "exec/cpu-defs.h"
 #include "qemu/cpu-float.h"
 
+/* MicroBlaze is always in-order. */
+#define TCG_GUEST_DEFAULT_MO  TCG_MO_ALL
+
 typedef struct CPUArchState CPUMBState;
 #if !defined(CONFIG_USER_ONLY)
 #include "mmu.h"