media: stm32-dcmi: revisit stop streaming ops

Do not wait for interrupt completion when stopping streaming,
stopping sensor and disabling interruptions are enough.

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+samsung@kernel.org>