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/packrl_ph.c

@@ -0,0 +1,21 @@
+#include<stdio.h>
+#include<assert.h>
+
+int main()
+{
+    int rd, rs, rt;
+    int result;
+
+    rs = 0x12345678;
+    rt = 0x87654321;
+    result = 0x56788765;
+
+    __asm
+        ("packrl.ph %0, %1, %2\n\t"
+         : "=r"(rd)
+         : "r"(rs), "r"(rt)
+        );
+    assert(result == rd);
+
+    return 0;
+}