MIPS64: Remove the workaround in VisitInvokeStaticOrDirect

This is not needed since $s2-$s8 are not blocked any more. This is
follow-up change for I325ab403752c6b9cd788147cb8b21d42aaff629e.

Change-Id: I934a21adb85581e137a6dcb3355605742b085d83
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index 5587351..2330c48 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -2983,19 +2983,6 @@
   }
 
   HandleInvoke(invoke);
-
-  // While SetupBlockedRegisters() blocks registers S2-S8 due to their
-  // clobbering somewhere else, reduce further register pressure by avoiding
-  // allocation of a register for the current method pointer like on x86 baseline.
-  // TODO: remove this once all the issues with register saving/restoring are
-  // sorted out.
-  if (invoke->HasCurrentMethodInput()) {
-    LocationSummary* locations = invoke->GetLocations();
-    Location location = locations->InAt(invoke->GetSpecialInputIndex());
-    if (location.IsUnallocated() && location.GetPolicy() == Location::kRequiresRegister) {
-      locations->SetInAt(invoke->GetSpecialInputIndex(), Location::NoLocation());
-    }
-  }
 }
 
 static bool TryGenerateIntrinsicCode(HInvoke* invoke, CodeGeneratorMIPS64* codegen) {