drm/client: s/unsigned int i/int i/

Replace the 'unsigned int i' footguns with plain old signed
int. Avoids accidents if/when someone decides they need
to iterate backwards.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250228211454.8138-9-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>