media: dt-bindings: Fix vendor-prefixes YAML

Commit 8df39e16 ("media: dt-bindings: media: Add vendor prefix for
allegro") introduced a new devicetree binding vendors, however with an
improper syntax making the resulting YAML impossible to parse. Let's fix
this.

Fixes: 8df39e16 ("media: dt-bindings: media: Add vendor prefix for allegro")

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>