media: tc358746: Use the correct div_ function

fin does not fit in 32 bits in some arches.

Found by cocci:
drivers/media/i2c/tc358746.c:847:2-8: WARNING: do_div() does a 64-by-32 division, please consider using div64_ul instead.

Link: https://lore.kernel.org/linux-media/20240429-fix-cocci-v3-22-3c4865f5a4b0@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>