power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth

power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth

For supporting bluetooth over the non-discoverable UART interface of
WCN7850, create the serdev device after enumerating the PCIe interface.
This is mandatory since the device ID is only known after the PCIe
enumeration and the ID is used for creating the serdev device.

Since by default there is no OF or ACPI node for the created serdev,
create a dynamic OF 'bluetooth' node with the 'compatible' property and
attach it to the serdev device. This will allow the serdev device to bind
to the existing bluetooth driver.

Tested-by: Hans de Goede <johannes.goede@oss.qualcomm.com> # ThinkPad T14s gen6 (arm64)
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20260326-pci-m2-e-v7-8-43324a7866e6@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>