ARM: dts: qcom: msm8974: castor: Add Bluetooth-related nodes

Castor has a BCM4339 attached to BLSP2 UART7, add the necessary nodes to
define the uart as well as the serdev BCM.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Julian Weigt <juw@posteo.de>
Link: https://lore.kernel.org/r/20210723202101.65371-2-juw@posteo.de


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>