Bluetooth: MAINTAINERS: add Devicetree bindings to Bluetooth drivers

The Devicetree bindings should be picked up by subsystem maintainers,
but respective pattern for Bluetooth drivers was missing.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>