media: s5p-jpeg: Handle parsing error in s5p_jpeg_parse_hdr()

This patch modifies the s5p_jpeg_parse_hdr() function so it only
modifies the passed s5p_jpeg_q_data structure if the jpeg header parsing
is successful.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Acked-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>