[media] coda: drop JPEG buffers not framed by SOI and EOI markers

This patch adds a quick check for valid JPEG frames before feeding them into
the bitstream buffer: Frames that do not begin with the JPEG start of image
marker and end with the end of image marker are dropped.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>