drm/fourcc: Fix the parameters name in the documentation

We introduced new functions in the commit bf39607c ("drm/fourcc: Pass
the format_info pointer to drm_format_plane_width/height") based on
previous ones but with a slightly different prototype. However, the
documentation wasn't changed to reflect that change.

Fixes: bf39607c ("drm/fourcc: Pass the format_info pointer to drm_format_plane_width/height")
Reported-by: kbuild test robot <lkp@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190521110906.15268-1-maxime.ripard@bootlin.com