replace the NR_DL_FRAME_PARMS structure into the NR_DL_FRAME_PARMS structure pointer

function nr_generate_dci_top and nr_generate_dci has the frame_parms parameter, which type is the structure NR_DL_FRAME_PARMS. It will lead to new space allocated if the structure is passed into the parameter. Thus, much time is elapsed (It may spend 100~400 us on this passing parameter). The better way is acting the parameter as a pointer. If so, it only spends 3 us on the passing parameter.