[AMDGPU] Remove miscellaneous unused code. NFC.

Author: jayfoad

llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp

@@ -3076,11 +3076,7 @@ void AMDGPURegisterBankInfo::applyMappingImpl(
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_OR:
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_XOR:
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_INC:
-  case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_DEC: {
-    applyDefaultMapping(OpdMapper);
-    executeInWaterfallLoop(B, MI, {2, 5});
-    return;
-  }
+  case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_DEC:
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_FADD:
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_FMIN:
   case AMDGPU::G_AMDGPU_BUFFER_ATOMIC_FMAX: {

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -10013,8 +10013,6 @@ SDValue SITargetLowering::bufferRsrcPtrToVector(SDValue MaybePointer,
   if (!MaybePointer.getValueType().isScalarInteger())
     return MaybePointer;
 
-  SDLoc DL(MaybePointer);
-
   SDValue Rsrc = DAG.getBitcast(MVT::v4i32, MaybePointer);
   return Rsrc;
 }