DRM: Fix an incorrectly formatted table

The "supported input formats" table in dw_hdmi.h was incorrectly formatted,
using "+" signs where "|" needs to be.  That, in turn, causes the PDF build
to fail.

Fixes: def23aa7

 ("drm: bridge: dw-hdmi: Switch to V4L bus format and encodings")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170623140013.0703107a@lwn.net