MINOR: stconn: Call sc_conn_process from the I/O callback if TASK_WOKEN_MSG state...

MINOR: stconn: Call sc_conn_process from the I/O callback if TASK_WOKEN_MSG state was set

It is the first commit of a series to refactor the SC app_ops. The first
step is to remove the .wake() callback function from the app_ops to replace
all uses by a wakeup of the SC tasklet.

Here, when the SC is woken up, the state is now tested and if TASK_WOKEN_MSG
is set, sc_conn_process() is called.