Currently the header argument is being passed by value, so a copy of 256
byte structure on the stack is potentially occurring. Fix this by passing
by reference to avoid any large stack copies.

Addresses-Coverity: ("Big parameter passed by value")

Fixes: 2db16c6e ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>