[media] Fix VIDIOC_TRY_EXT_CTRLS regression

Fixes an omission in the new v4l2_ioctls table: VIDIOC_TRY_EXT_CTRLS
must get the INFO_FL_CTRL flag, just like all the other control
related ioctls, otherwise the ioctl core won't know it also has
to check whether v4l2_fh->ctrl_handler is non-zero before it can
decide that this ioctl is not implemented.

Caught by v4l2-compliance while I was testing the mem2mem_testdev driver.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>