media: staging: media: ipu3: Change 'unsigned long int' to 'unsigned long'

This patch fixes the checkpatch.pl warning:

WARNING: Prefer 'unsigned long' over 'unsigned long int' as the int is
unnecessary

Signed-off-by: Jean-Baptiste Jouband <jj.jouband@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>