Camera3: Fix Bug minTimestamp is never greater than frame timestamp

Bug in logic since minTimestamp is initialized to -1, and this needs
to be updated for the first frame atleast for logic to work correctly
for subsequent frames.

Bug: 9007356
Change-Id: I70edc4d9f34ff67a141c027c67396dc2ca9e413a
Signed-off-by: Igor Murashkin <iam@google.com>