[Bugfix] Assign Target for jit kernel (#648)

* fix: Copy Target to self.target

* refactor: Remove unused target attribute and adjust context management in JITKernel

- Removed the unused `target` attribute from the `JITKernel` class.
- Updated the context management in the `compile` method to utilize `self.target`, improving clarity and ensuring proper resource handling during compilation.

---------
Co-authored-by: LeiWang1999 <leiwang1999@outlook.com>

tilelang/jit/kernel.py

@@ -75,7 +75,6 @@ class JITKernel(object):
         """
         self.prim_func = func
         self.execution_backend = execution_backend
-        self.target = target
         self.target_host = target_host
         self.verbose = verbose
 
@@ -89,7 +88,7 @@ class JITKernel(object):
             target = determine_target(target)
 
         # Ensure the target is always a TVM Target object.
-        target = Target(target)
+        self.target = Target(target)
 
         # Validate the execution backend.
         assert execution_backend in [
@@ -196,7 +195,7 @@ class JITKernel(object):
         # Compile the function with TVM, optimizing with shared memory lowering.
         enable_host_codegen = execution_backend == "dlpack"
         enable_device_compile = execution_backend == "dlpack"
-        with tvm.transform.PassContext(opt_level=3, config=pass_configs):
+        with tvm.transform.PassContext(opt_level=3, config=pass_configs), self.target:
             artifact = tilelang.lower(
                 tilelang_func,
                 target=target,