media: coda: avoid hardware lockups with more than 13 capture buffers

When decoding using the CODA internal rotator (for example NV12
capture), currently the value vb2_buf.index + CODA_MAX_FRAMEBUFFERS (19)
is written into the DEC_PIC_ROT_INDEX register. At least with firmware
version 3.1.1 this causes CODA hangups as soon as the register value
reaches 32. Instead, always write CODA_MAX_FRAMEBUFFERS.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>