rmnet_smux: device state check condition removed

If SSR happens in high watermark hit case, then the high-watermark-hit
condition is not reset correctly which causes TX data stall after
recovered from SSR.

In the SSR case, SMUX sends disconnect event to clients. For this event,
the RMNET client changes the device state to INACTIVE which prevents
call to msm_smux_close() from smux_rmnet_remove().

Remove the device state check condtion to iopen and close the RMNET
logical channel during RMNET device probe and remove.

CRs-fixed: 465510
Change-Id: I4dded65d41af4415f2427da388a59de4a1980a29
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>