sensorservice: Fix init sequence for pre-1.1 API sensor HALs

The sensors API introduced a new flush() method that older binaries
won't have. For those, replace the firstFlush invocation with a
setDelay call since a lot of implementations interpreted that as
the initialization step.
We also don't want any kind of call to flush() to happen when it
isn't there, since it'll either hit a random OEM extension or
a memory address we really don't want to execute.

Change-Id: I26ce923fe385751fed7d1c483a53c074249f0620
SurfaceFlinger: Add NULL check for buffer handling

Add buffer handling NULL check in dequeueBuffer and
verify whether the output data from binder is not NULL
in queueBuffer and connect api's to avoid SF crash

CRs-Fixed: 573088
CRs-Fixed: 572315

Change-Id: I41cebbc0cbcbbb0fd5ecb38db7ec7b0c91cdffe9