media: qcom: camss: vfe: Move common code into vfe core

Some v4l2 buffer related logic functions can be moved to vfe core as
common code, then the vfe driver of different hw version can reuse them,
this also can avoid adding duplicate code for new version supporting.

Suggested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Depeng Shao <quic_depengs@quicinc.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>