drm/rockchip/rockchip_lvds: Fix struct document formatting

Must start with "struct <name>"

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

drivers/gpu/drm/rockchip/rockchip_lvds.c:49: warning: cannot understand function prototype: 'struct rockchip_lvds_soc_data '

Cc: Sandy Huang <[e-mail]>
Cc: "Heiko Stübner" <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Mark Yao <[e-mail]>
Cc: [e-mail]
Cc: [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/rockchip/rockchip_lvds.c

···
 		container_of(c, struct rockchip_lvds, encoder)
 
 /**
- * rockchip_lvds_soc_data - rockchip lvds Soc private data
+ * struct rockchip_lvds_soc_data - rockchip lvds Soc private data
  * @probe: LVDS platform probe function
  * @helper_funcs: LVDS connector helper functions
  */