icnss: Ignore server exit if already in progress

This change is to avoid back to back server exit/arrive call
from qmi framework. It also ensures that server arrive is
processed only after releasing qmi handle after SSR/PDR.

Change-Id: I4a12625d61ac64d00da70cf6fbecce7c6cf75348
Signed-off-by: Sandeep Singh <sandsing@codeaurora.org>