Include <drm/*.h> instead of relative path from include/drm, then
remove the -Iinclude/drm compiler flag.

While we are here, sort the touched parts alphabetically.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1493009447-31524-7-git-send-email-yamada.masahiro@socionext.com