target-mips: Add ASE DSP testcases

Add MIPS ASE DSP testcases.

Signed-off-by: Jia Liu <proljc@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

tests/tcg/mips/mips64-dsp/mthi.c

@@ -0,0 +1,24 @@
+#include "io.h"
+
+int main(void)
+{
+    long long achi, acho;
+    long long result;
+
+    achi   = 0x004433;
+    result = 0x004433;
+
+    __asm
+        ("mthi %1, $ac1\n\t"
+         "mfhi %0, $ac1\n\t"
+         : "=r"(acho)
+         : "r"(achi)
+        );
+    if (result != acho) {
+        printf("mthi wrong\n");
+
+        return -1;
+    }
+
+    return 0;
+}