pci: Enable GSI routing (MSI type) for AArch64

In this commit we saved the BDF of a PCI device and set it to "devid"
in GSI routing entry, because this field is mandatory for GICv3-ITS.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>

vm-device/src/interrupt/mod.rs

@@ -83,6 +83,8 @@ pub struct MsiIrqSourceConfig {
     pub low_addr: u32,
     /// Data to write to delivery message signaled interrupt.
     pub data: u32,
+    /// Unique ID of the device to delivery message signaled interrupt.
+    pub devid: u32,
 }
 
 /// Configuration data for an interrupt source.