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/mips32-dsp/subu_qb.c

@@ -0,0 +1,25 @@
+#include<stdio.h>
+#include<assert.h>
+
+int main()
+{
+    int rd, rs, rt, dsp;
+    int result, resultdsp;
+
+    rs = 0x12345678;
+    rt = 0x87654321;
+    result    = 0x8BCF1357;
+    resultdsp = 0x01;
+
+    __asm
+        ("subu.qb %0, %2, %3\n\t"
+         "rddsp   %1\n\t"
+         : "=r"(rd), "=r"(dsp)
+         : "r"(rs), "r"(rt)
+        );
+    dsp = (dsp >> 20) & 0x01;
+    assert(dsp == resultdsp);
+    assert(rd  == result);
+
+    return 0;
+}