Camera: fix an issue regarding ndk/vndk availability callback

If NDK user only uses availability callback then no service connection
will be made. Thus, no availability callback will be posted to the user.

Also, the camera service used to unconditionally filter out the status
change, if the listener is vendor listener. So, VNDK user will never
receive the availability callback.

With this patch, availability callback routine explicitly makes
connection to the service, and the status change will be filtered from
the service properly using shouldSkipStatusUpdates().

Test: use availability callback only from jni sample, vendor sample
Change-Id: Ic1d5951e3ee3b24ffe19aa780c67a98db781545b