media: rkvdec: Improve handling missing short/long term RPS

media: rkvdec: Improve handling missing short/long term RPS

The values of ext_sps_st_rps and ext_sps_lt_rps in struct rkvdec_hevc_run
are not initialized when the respective controls are not set by userspace.

When this is the case, set them to NULL so the rkvdec_hevc_run_preamble
function that parses controls does not access garbage data which leads to
a panic on unaccessible memory.

Fixes: c9a59dc2acc7 ("media: rkvdec: Add HEVC support for the VDPU381 variant")
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Suggested-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Tested-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>