msm: hdcp: do not return error if work is already queued

Apart from authentications start, if any other work is already
queued, do not return any error in that case as the work is
going to run eventually. This doesn't apply for authentication
start as last session should have been closed before new one
is started.

Change-Id: If5f61f05758135d303974f8bd824ffcc9387259d
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>