drm/rockchip: Drop unbalanced obj unref

stable inclusion
from stable-v5.10.180
commit ae784c3ed37384210a43529f7842c865581c1258
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8DDFN

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ae784c3ed37384210a43529f7842c865581c1258



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[ Upstream commit 8ee3b0e8 ]

In the error path, rockchip_drm_gem_object_mmap() is dropping an obj
reference that it doesn't own.

Fixes: 41315b79 ("drm/rockchip: use drm_gem_mmap helpers")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230119231734.2884543-1-robdclark@gmail.com


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>