[MLIR][SPIRV] Fixed dialect loading in deserialization

[georgemitenkov]

Summary

Fixed an error when deserializing the SPIR-V binary
to MLIR SPIR-V. Before, the SPIR-V dialect was not loaded
explicitly into the context, which resulted in unregisterd
operation error.

[antiagainst]

Thanks for the fix!

mlir/lib/Dialect/SPIRV/Serialization/TranslateRegistration.cpp

 //===----------------------------------------------------------------------===//
 // Deserialization registration
 //===----------------------------------------------------------------------===//
 
 // Deserializes the SPIR-V binary module stored in the file named as
 // `inputFilename` and returns a module containing the SPIR-V module.
 static OwningModuleRef deserializeModule(const llvm::MemoryBuffer *input,
                                          MLIRContext *context) {
-  Builder builder(context);
+  context->loadDialect<spirv::SPIRVDialect>();
 
   // Make sure the input stream can be treated as a stream of SPIR-V words
   auto start = input->getBufferStart();
   auto size = input->getBufferSize();
   if (size % sizeof(uint32_t) != 0) {
     emitError(UnknownLoc::get(context))
         << "SPIR-V binary module must contain integral number of 32-bit words";
     return {};