Bluetooth: btbcm: Rewrite bindings in YAML and add reset

This rewrites the Broadcom bluetooth bindings in YAML and
adds a GPIO handle for the BT_RST_N line as used on some
platforms.

The Ingenic UART binding was using this binding in its
example DTS fragment, however mistakenly using "vcc-supply"
for what is called "vbat-supply". The proper DTS files
and the code in the kernel all use "vbat-supply" so
fix up the example in this patch so we ge a clean
check.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>