qseecom: do not wake up listener to receive request if it is not ready

Listener should not process the old pending listener request that
was received when listener is not ready, as shared buffer may be
locked at this time.

Change-Id: Ib954143aa19c61b6a1a24206182cd8a8469546d2
Signed-off-by: Zhen Kong <zkong@codeaurora.org>