CLEANUP: stconn: rename SE_FL_RX_WAIT_EP to SE_FL_HAVE_NO_DATA

It's more explicit this way. The cs_rx_endp_ready() function could be
removed so that the flag is directly tested. In the future it should
be inverted and the few places where it's set (or preserved via
SE_FL_APP_MASK) could be dropped.
6 files changed