msm: smd_tty: unblock poll() in case of SSR

If an SSR is triggered, then read() and write() system calls are
unblocked by sending a TTY_BREAK to the TTY framework.  However, poll()
is not unblocked unless an error flag is set.

Set the TTY_OTHER_CLOSED bit to unblock poll().

CRs-Fixed: 546063
Change-Id: Ibe7cb16b61807b679593beee28c5032e56cc79da
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>