media: dt-bindings: ak7375: Add supplies

Add supply properties to describe regulators needed to power
the AK7375 VCM.

Signed-off-by: Yassine Oudjana <y.oudjana@protonmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>