drm: Fix htmldocs indentation warning w/ DP AUX power requirements

Two blank lines are needed to make the rst valid.

Fixes: 69ef4a19 ("drm: Document the power requirements for DP AUX transfers")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220611095445.1.I534072d346b1ebbf0db565b714de9b65cbb24651@changeid