media: ipu3-imgu: Use %u for formatting unsigned values (not %d)

The driver used %d for formatting unsigned values. Use %u instead.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>