msm: ipa3: Added changes to check QMI pointer valid or not

After passing ipa_q6_clnt pointer to function, if it freed in
different thread it may lead to NULL pointer access. So adding
check to see passed pointer valid or not.

Change-Id: I22e272ebdecc62756ee140081524ab4efdd3d02a
Signed-off-by: Ashok Vuyyuru <quic_avuyyuru@quicinc.com>