When adding an internal scratch buffer to improve buffer handling when
stopping it was also erroneously used when syncing at capture start.
This led to that the first three buffers captured were always dropped
as they were captured in the scratch buffer instead of in a buffer
provided by the user.

Allow the hardware to be given user provided buffers when preparing for
capture in the stopped state. This still allows the driver to sync with
the hardware and always completes the buffers to user-space in the
correct order as no buffers are completed before the sync is complete.
This change improves the driver as buffers are completed and given to
the user three frames earlier than before.

The change also fixes a warning produced by v4l2-compliance,

    warn: v4l2-test-buffers.cpp(448): got sequence number 3, expected 0

[hverkuil: fixed some typos in the Subject and the log message]
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>