[NFC] Add myself to CODEOWNERS for AMD dialects (llvm#164289)

Having taken on a maintainer role for these dialects, make it official
with a CODEOWNERS entry.

---------

Co-authored-by: Jakub Kuderski <[email protected]>

Author: krzysz00

.github/CODEOWNERS

@@ -53,6 +53,13 @@
 /mlir/include/mlir/Interfaces/DestinationStyleOpInterface.* @matthias-springer
 /mlir/lib/Interfaces/DestinationStyleOpInterface.* @matthias-springer
 
+# AMDGPU and ROCDL dialects in MLIR.
+/mlir/include/mlir/Dialect/AMDGPU @krzysz00 @kuhar
+/mlir/lib/Dialect/AMDGPU @krzysz00 @kuhar
+/mlir/lib/Conversion/*AMDGPU* @krzysz00 @kuhar
+/mlir/lib/Conversion/*ToROCDL @krzysz00 @kuhar
+/mlir/include/mlir/Dialect/LLVMIR/ROCDL* @krzysz00 @kuhar
+
 # Bufferization Dialect in MLIR.
 /mlir/include/mlir/Dialect/Bufferization @matthias-springer
 /mlir/lib/Dialect/Bufferization @matthias-springer