[SYCL][Fusion] Silence warning

[jopperm]

Silence unused variable warning which tripped post-commit checks for #12492.

[aelovikov-intel]

Post commit failures on Arc GPU (for future references/searches):

Failed Tests (3):
  SYCL :: ESIMD/lsc/local_accessor_atomic_smoke_cmpxchg.cpp
  SYCL :: ESIMD/lsc/lsc_slm_atomic_smoke.cpp
  SYCL :: OneapiDeviceSelector/level_zero_top.cpp

Last test failed like this:

FAIL: SYCL :: OneapiDeviceSelector/level_zero_top.cpp (1406 of 1854)
******************** TEST 'SYCL :: OneapiDeviceSelector/level_zero_top.cpp' FAILED ********************
Exit Code: -6

Command Output (stdout):
--
# RUN: at line 2
/__w/llvm/llvm/toolchain/bin//clang++   -fsycl -fsycl-targets=spir64 /__w/llvm/llvm/llvm/sycl/test-e2e/OneapiDeviceSelector/level_zero_top.cpp -o /__w/llvm/llvm/build-e2e/OneapiDeviceSelector/Output/level_zero_top.cpp.tmp.out
# executed command: /__w/llvm/llvm/toolchain/bin//clang++ -fsycl -fsycl-targets=spir64 /__w/llvm/llvm/llvm/sycl/test-e2e/OneapiDeviceSelector/level_zero_top.cpp -o /__w/llvm/llvm/build-e2e/OneapiDeviceSelector/Output/level_zero_top.cpp.tmp.out
# note: command had no output on stdout or stderr
# RUN: at line 3
env ONEAPI_DEVICE_SELECTOR=level_zero:gpu  /__w/llvm/llvm/build-e2e/OneapiDeviceSelector/Output/level_zero_top.cpp.tmp.out
# executed command: env ONEAPI_DEVICE_SELECTOR=level_zero:gpu /__w/llvm/llvm/build-e2e/OneapiDeviceSelector/Output/level_zero_top.cpp.tmp.out
# .---command stdout------------
# | Level-Zero GPU Device is found: true
# | Intel(R) Level-Zero is found: true
# | Expectedly, cpu device is not found.
# | Expectedly, ACC device is not found.
# | Abort was called at 253 line in file:
# | ../../neo/level_zero/core/source/builtin/builtin_functions_lib_impl.cpp
# `-----------------------------
# .---command stderr------------
# | pure virtual method called
# | terminate called without an active exception
# `-----------------------------
# error: command failed with exit status: -6