drm/vgem: add missing mutex_destroy

stable inclusion
from stable-v5.10.180
commit 67f07215eb8b19cab11dc0929c06c71e069afbcf
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=67f07215eb8b19cab11dc0929c06c71e069afbcf



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

[ Upstream commit 7c18189b ]

vgem_fence_open() instantiates a mutex for a particular fence
instance, but never destroys it by calling mutex_destroy() in
vgem_fence_close().

So, add the missing mutex_destroy() to guarantee proper resource
destruction.

Fixes: 40777984 ("drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)")
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230202125517.427976-1-mcanal@igalia.com


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