MIPS64: Add missing instructions to disasm-mips64.cc

Add SDL and SDR instructions to disassembler on MIPS64.

Bug: 
Change-Id: I9cfcfe05d34aa483b8f7504267b76a782dd06558
Reviewed-on: https://chromium-review.googlesource.com/856676Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#50429}

src/mips64/disasm-mips64.cc

@@ -2225,6 +2225,12 @@ void Decoder::DecodeTypeImmediate(Instruction* instr) {
     case SWR:
       Format(instr, "swr     'rt, 'imm16s('rs)");
       break;
+    case SDR:
+      Format(instr, "sdr     'rt, 'imm16s('rs)");
+      break;
+    case SDL:
+      Format(instr, "sdl     'rt, 'imm16s('rs)");
+      break;
     case LL:
       if (kArchVariant == kMips64r6) {
         Unknown(instr);