drm/kms-core: Use recommened kerneldoc for struct member refs

I just learned that &struct_name.member_name works and looks pretty
even. It doesn't (yet) link to the member directly though, which would
be really good for big structures or vfunc tables (where the
per-member kerneldoc tends to be long).

Also some minor drive-by polish where it makes sense, I read a lot
of docs ...

v2: Review from Eric.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170125062657.19270-4-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_encoder_slave.c b/drivers/gpu/drm/drm_encoder_slave.c
index 4484785..cf80438 100644
--- a/drivers/gpu/drm/drm_encoder_slave.c
+++ b/drivers/gpu/drm/drm_encoder_slave.c
@@ -43,7 +43,7 @@
  * &drm_encoder_slave. The @slave_funcs field will be initialized with
  * the hooks provided by the slave driver.
  *
- * If @info->platform_data is non-NULL it will be used as the initial
+ * If @info.platform_data is non-NULL it will be used as the initial
  * slave config.
  *
  * Returns 0 on success or a negative errno on failure, in particular,