drm/amd/display: Add null check for pipe_ctx->plane_state in dcn20_program_pipe

stable inclusion
from stable-v6.11.3
commit 65a6fee22d5cfa645cb05489892dc9cd3d142fc2
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRAY
CVE: CVE-2024-49914

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=65a6fee22d5cfa645cb05489892dc9cd3d142fc2



--------------------------------

[ Upstream commit 8e4ed3cf1642df0c4456443d865cff61a9598aa8 ]

This commit addresses a null pointer dereference issue in the
`dcn20_program_pipe` function. The issue could occur when
`pipe_ctx->plane_state` is null.

The fix adds a check to ensure `pipe_ctx->plane_state` is not null
before accessing. This prevents a null pointer dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn20/dcn20_hwseq.c:1925 dcn20_program_pipe() error: we previously assumed 'pipe_ctx->plane_state' could be null (see line 1877)

Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Conflicts:
	drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
	drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
[The stable version 5.10 is missing patch 65a6fee22d5cfa645cb05489892dc9cd3d142fc2,
which was pulled from 6.11. Manually removed unnecessary code, such as
if (pipe_ctx->update_flags.bits.det_size),
if (hws->funcs.populate_mcm_luts),
if (pipe_ctx->update_flags.bits.enable),
if ((pipe_ctx->plane_state && pipe_ctx->plane_state->visible)).
The purpose of this patch is to check if pipe_ctx->plane_state is not
null before using its properties. Other extraneous code from higher
versions is unrelated to the current patch and has been removed.]
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>