Camera API1: remove unnecessary buffer count check

This check doesn't work with ZSL use case. Since the ZSL is both an input and
output stream, When an input buffer is acquired, checking the handout buffer
count for that stream could trigger false alarm when all the output buffers
are sent to hal, instead, we should wait for an output buffer to return.

Bug: 17188380
Change-Id: I7eb166eb49d2f063189d993195ef389d2cf4f2b4