media: s5p-jpeg: don't overwrite result's "size" member

Originally the "size" member was modified in a local variable passed to
s5p_jpeg_parse_hdr() but the member was not used by the caller, so it did
not matter. After applying patch
"media: s5p-jpeg: Don't use temporary structure in s5p_jpeg_buf_queue"
the unnecessary assignment started overwriting already assigned "size"
member of the passed structure with an incorrect value.

Fixes: 14a2de14 ("media: s5p-jpeg: Don't use temporary structure in s5p_jpeg_buf_queue")

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>