v4l2-ioctl: clear the reserved field of v4l2_create_buffers

v4l2-ioctl: clear the reserved field of v4l2_create_buffers

This field was never cleared by the kernel making future extensions
hard to implement. Clear it now.

Bug 200184254

Change-Id: Ie549f6418be24b452e2d0d1d423287279529054d
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
(cherry picked from commit f9c4310c11f57252cf50d8b7ab85e0609762562c)
Reviewed-on: http://git-master/r/1118313
Signed-off-by: Bryan Wu <pengw@nvidia.com>
Reviewed-on: http://git-master/r/1141884
GVS: Gerrit_Virtual_Submit
Reviewed-by: Jihoon Bang <jbang@nvidia.com>