CLEANUP: sched: remove duplicate code in run_tasks_from_list()

CLEANUP: sched: remove duplicate code in run_tasks_from_list()

Now that ->wake_date is common to tasks and tasklets, we don't need
anymore to carry a duplicate control block to read and update it for
tasks and tasklets. And given that this code was present early in the
if/else fork between tasks and tasklets, taking it out of the block
allows to move the task part into a more visible "else" branch that
also allows to factor the epilogue that resets th_ctx->current and
updates profile_entry->cpu_time, which also used to be duplicated.

Overall, doing just that saved 253 bytes in the function, or ~1/6,
which is not bad considering that it's on a hot path. And the code
got much ore readable.