[media] s5p-jpeg: don't return a random width/height

[media] s5p-jpeg: don't return a random width/height

Gcc 7.1 complains about:

drivers/media/platform/s5p-jpeg/jpeg-core.c: In function 's5p_jpeg_parse_hdr.isra.9':
drivers/media/platform/s5p-jpeg/jpeg-core.c:1207:12: warning: 'width' may be used uninitialized in this function [-Wmaybe-uninitialized]
  result->w = width;
  ~~~~~~~~~~^~~~~~~
drivers/media/platform/s5p-jpeg/jpeg-core.c:1208:12: warning: 'height' may be used uninitialized in this function [-Wmaybe-uninitialized]
  result->h = height;
  ~~~~~~~~~~^~~~~~~~

Indeed the code would allow it to return a random value (although
it shouldn't happen, in practice). So, explicitly set both to zero,
just in case.

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