Load store unit todo removal and refactor

Created by: silabs-oysteink

Removed local lsu_en_gated from the load_store_unit, as this is equivalent to valid_0_i computed in the EX stage.

Refactored LSU ready_1_0, done_0 and valid_0_o.

SEC clean.

Signed-off-by: Oystein Knauserud Oystein.Knauserud@silabs.com