media: stm32-dcmi: increase max width/height to 2592

DCMI can capture 5Mp raw frames, increase limit accordingly.

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>