Add SYCLDialect to polygeist-opt (#42)

`polygeist-opt` is useful to call specific pass(es). This PR adds the `SYCLDialect` to `polygeist-opt`.
Before this PR, if the input MLIR contains SYCL dialect, it would fail with e.g.,
```
error: ... type created with unregistered dialect. ...
```
Example of using `polygeist-opt`:
```
sycl-mlir/build/bin/polygeist-opt t.mlir -convert-polygeist-to-llvm
```

Signed-off-by: Tsang, Whitney <[email protected]>

Author: whitneywhtsang

polygeist/tools/polygeist-opt/CMakeLists.txt

@@ -6,6 +6,7 @@ set(LIBS
         MLIROptLib
 		MLIRPolygeist
 		MLIRPolygeistTransforms
+        MLIRSYCLDialect
         )
 add_llvm_executable(polygeist-opt polygeist-opt.cpp)
 

polygeist/tools/polygeist-opt/polygeist-opt.cpp

@@ -24,6 +24,7 @@
 #include "mlir/Dialect/MemRef/IR/MemRef.h"
 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "mlir/Dialect/SCF/IR/SCF.h"
+#include "mlir/Dialect/SYCL/IR/SYCLOpsDialect.h"
 #include "mlir/InitAllPasses.h"
 #include "mlir/Pass/PassRegistry.h"
 #include "mlir/Tools/mlir-opt/MlirOptMain.h"
@@ -60,6 +61,7 @@ int main(int argc, char **argv) {
   registry.insert<DLTIDialect>();
 
   registry.insert<mlir::polygeist::PolygeistDialect>();
+  registry.insert<mlir::sycl::SYCLDialect>();
 
   mlir::registerpolygeistPasses();