arm64: dts: qcom: sm7225-fairphone-fp4: Add Bluetooth

The device has a WCN3988 chip for WiFi and Bluetooth. Configure the
Bluetooth node and enable the UART it is connected to, plus the
necessary pinctrl that has been borrowed with comments from
sc7280-idp.dtsi.

Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230421-fp4-bluetooth-v2-4-3de840d5483e@fairphone.com