PPC [disas]: fix mtvsrdd on disassembler

mtvsrdd uses 2 gprs as input.

Change-Id: I4446a51bda1196ce262e3a90ed7c840da89c9d16
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3061478Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#76009}

src/diagnostics/ppc/disasm-ppc.cc

@@ -1124,7 +1124,7 @@ void Decoder::DecodeExt2(Instruction* instr) {
       return;
     }
     case MTVSRDD: {
-      Format(instr, "mtvsrdd 'Xt, 'ra");
+      Format(instr, "mtvsrdd 'Xt, 'ra, 'rb");
       return;
     }
     case LDBRX: {