CLEANUP: stconn: rename remaining management functions from cs_* to sc_*

CLEANUP: stconn: rename remaining management functions from cs_* to sc_*

This is the end of the renaming for the generic SC management functions
and macros:

cs_applet_process() -> sc_applet_process()
cs_attach_applet()  -> sc_attach_applet()
cs_attach_mux()     -> sc_attach_mux()
cs_attach_strm()    -> sc_attach_strm()
cs_detach_app()     -> sc_detach_app()
cs_detach_endp()    -> sc_detach_endp()
cs_notify()         -> sc_notify()
cs_reset_endp()     -> sc_reset_endp()
cs_state_in()       -> sc_state_in()
cs_update()         -> sc_update()
cs_update_rx()      -> sc_update_rx()
cs_update_tx()      -> sc_update_tx()
IS_HTX_CS()         -> IS_HTX_SC()