[SYCL] Fix incorrect return of PropertyValue::data() (#18944)

The data function of PropertyValue was returning a pointer to a pointer
when the underlying data was a byte array, rather than returning the
byte array pointer itself. This commit fixes the return value for the
byte array case.

---------

Signed-off-by: Larsen, Steffen <steffen.larsen@intel.com>

Author: Steffen Larsen

llvm/include/llvm/Support/PropertySetIO.h

@@ -158,7 +158,16 @@ class PropertyValue {
     }
   }
 
-  const char *data() const { return reinterpret_cast<const char *>(&Val); }
+  const char *data() const {
+    switch (Ty) {
+    case UINT32:
+      return reinterpret_cast<const char *>(&Val.UInt32Val);
+    case BYTE_ARRAY:
+      return reinterpret_cast<const char *>(Val.ByteArrayVal);
+    default:
+      llvm_unreachable_internal("unsupported property type");
+    }
+  }
 
 private:
   template <typename T> T &getValueRef();