media: stm32-dcmi: rework overrun/error case

Do not stop/restart dma on overrun or errors.
Dma will be restarted on current frame transfer
completion. Frame transfer completion is ensured
even if overrun or error occurs by DCMI continuous
capture mode which restarts data transfer at next
frame sync.
Do no warn on overrun while in irq thread, this slows down
system and lead to more overrun errors. Use a counter
instead and log errors at stop streaming.

Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>