package/libcamera-apps: fix overflow conversion error

Upstream commit:
https://github.com/raspberrypi/libcamera-apps/commit/a65682a97e19f96b86aeceb3ca3befb1687e3861

Fixes:
- http://autobuild.buildroot.net/results/758631a9fcd62835844f78914a36dfb579e7beba/



Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>