arm64: dts: qcom: qrb4210-rb2: describe WiFi/BT properly

arm64: dts: qcom: qrb4210-rb2: describe WiFi/BT properly

The onboard WiFi / BT device, WCN3988, has a simple on-chip PMU, which
further spreads generated voltage. Describe the PMU in the device tree.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260106-wcn3990-pwrctl-v2-11-0386204328be@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>