media: stb0899: Simplify check

chip_id is an unsigned number, it can never be < 0

Fixes cocci check:
drivers/media/dvb-frontends/stb0899_drv.c:1280:8-15: WARNING: Unsigned expression compared with zero: chip_id > 0

Link: https://lore.kernel.org/linux-media/20240429-fix-cocci-v3-2-3c4865f5a4b0@chromium.org
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>