fix windows xpu build issue (pytorch#133845)

# Motivation
If build XPU via oneAPI 2024.2, it will fail because `sycl-preview.lib` exists in windows. And linking the unexpected lib results in `error LNK2019: unresolved external symbol`.

# Solution
Use explicitly `sycl-preview` in linux build only.

# Additional Context
For `find_library`, please note that the variable will not be updated if it has been stored.
```
If the library is found the result is stored in the variable and the search will not be repeated unless the variable is cleared.
```

Pull Request resolved: pytorch#133845
Approved by: https://github.com/min-jean-cho, https://github.com/EikanWang, https://github.com/atalman, https://github.com/malfet

cmake/Modules/FindSYCLToolkit.cmake

@@ -49,12 +49,14 @@ find_file(
   )
 
 # Find SYCL library fullname.
-find_library(
-  SYCL_LIBRARY
-  NAMES sycl-preview
-  HINTS ${SYCL_LIBRARY_DIR}
-  NO_DEFAULT_PATH
-)
+if(LINUX)
+  find_library(
+    SYCL_LIBRARY
+    NAMES sycl-preview
+    HINTS ${SYCL_LIBRARY_DIR}
+    NO_DEFAULT_PATH
+  )
+endif()
 # On Windows, currently there's no sycl.lib. Only sycl7.lib with version suffix,
 # where the current version of the SYCL runtime is 7.
 # Until oneAPI adds support to sycl.lib without the version suffix,