msm: vidc: enhance eos buffer handling

Eos buffer is queued to firmware and its ref is maintained
using eosbufs.list. Sometimes EOS request client sent even
before port_reconfig. In that case requeing same buffer
which is already with firmware at start_streaming. So during
handle_ebd of 2nd eos buffer, it can't find the entry at
eosbufs.list. So client closes the session.

Always check, if buffer is already queued, then do not queue
the same buffer again, during start_streaming after reconfig.

Change-Id: If934d8ce357226dee78db15ccb7b3c57103d2f12
Signed-off-by: Govindaraj Rajagopal <grajagop@codeaurora.org>