media: coda: jpeg: only queue two buffers into the bitstream for JPEG on CODA7541

Padding the bitstream buffer is not enough to reliably avoid prefetch
failures.  Picture runs with the next buffer's header already visible to
the CODA7541 succeed much more reliably, so always queue two JPEG frames
into the bitstream buffer.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>