arm64: dts: meson-gxl-s905x-p212: add bluetooth nodes

This removes the uart_A alias (no longer required) and adds the bluetooth
node to the P212 device tree.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/1582216366-12964-1-git-send-email-christianshewitt@gmail.com