drm/vc4/vc4_v3d: Demote non-conformant kernel-doc headers

Fixes the following W=1 kernel build warning(s):

drivers/gpu/drm/vc4/vc4_v3d.c:131: warning: Function parameter or member 'vc4' not described in 'vc4_v3d_pm_get'
drivers/gpu/drm/vc4/vc4_v3d.c:231: warning: Function parameter or member 'vc4' not described in 'bin_bo_alloc'

Cc: Eric Anholt <[e-mail]>
Cc: Maxime Ripard <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Rob Clark <[e-mail]>
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/vc4/vc4_v3d.c

···
 	return 0;
 }
 
-/**
+/*
  * Wraps pm_runtime_get_sync() in a refcount, so that we can reliably
  * get the pm_runtime refcount to 0 in vc4_reset().
  */
···
 	return -ENOMEM;
 }
 
-/**
+/*
  * bin_bo_alloc() - allocates the memory that will be used for
  * tile binning.
  *