SYCL: Remove misleading ggml_sycl_op_flatten function (#12387)
* SYCL: Remove misleading ggml_sycl_op_flatten function
* remove trailing whitespace
* Fix L2 norm from rebase
* remove try catch block from element_wise.cpp
* remove comment from common.hp
* ggml-sycl.cpp: Add try catch sycl::exception block in compute_forward
* norm.cpp: remove try catch exception block