drm/msm: msm_fence.h: fix all kernel-doc warnings

drm/msm: msm_fence.h: fix all kernel-doc warnings

Correct or add kernel-doc comments to eliminate all warnings:

Warning: drivers/gpu/drm/msm/msm_fence.h:27 Incorrect use of kernel-doc
 format: * last_fence:
Warning: drivers/gpu/drm/msm/msm_fence.h:36 Incorrect use of kernel-doc
 format: * completed_fence:
Warning: drivers/gpu/drm/msm/msm_fence.h:44 Incorrect use of kernel-doc
 format: * fenceptr:
Warning: drivers/gpu/drm/msm/msm_fence.h:65 Incorrect use of kernel-doc
 format: * next_deadline_fence:
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'dev' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'name' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'context' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'index' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'fence' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'there is no
 remaining pending work */ uint32_t last_fence' not described in
 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'updated from the CPU after interrupt * from GPU */ uint32_t completed_fence' not described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'fenceptr' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'spinlock' not
 described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'next_deadline'
 not described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member
 'next_deadline_fence' not described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'deadline_timer'
 not described in 'msm_fence_context'
Warning: drivers/gpu/drm/msm/msm_fence.h:74 struct member 'deadline_work'
 not described in 'msm_fence_context'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/695667/
Link: https://lore.kernel.org/r/20251219184638.1813181-17-rdunlap@infradead.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>