CLEANUP: conn_stream: remove unneeded exclusion of RX_WAIT_EP from RXBLK_ANY

CLEANUP: conn_stream: remove unneeded exclusion of RX_WAIT_EP from RXBLK_ANY

This test in cs_update_rx() was introduced in 1.9 by commit b26a6f970
("MEDIUM: stream-int: make use of si_rx_chan_{rdy,blk} to control the
stream-int from the channel"), but by then already it was not needed
because the RX_WAIT_EP flag has never been part of RXBLK_ANY so there's
no point doing "flags & RXBLK_ANY & ~RX_WAIT_EP", that part is already
complicated enough like this.