misc: Change cpu ID type from u8 to u32

This is the first change to Cloud Hypervisor in a series of changes
intended to increase the max number of supported vCPUs in guest VMs,
which is currently limited to 255 (254 on x86_64).

No user-visible/behavior changes are expected as a result of
applying this patch, as the type of boot_cpus and related
fields in config structs remains u8 for now, and all configuration
validations remain the same.

Signed-off-by: Barret Rhoden <brho@google.com>
Signed-off-by: Neel Natu <neelnatu@google.com>
Signed-off-by: Ofir Weisse <oweisse@google.com>
Signed-off-by: Peter Oskolkov <posk@google.com>

devices/src/aia.rs

@@ -40,7 +40,7 @@ pub struct Aia {
 
 impl Aia {
     pub fn new(
-        vcpu_count: u8,
+        vcpu_count: u32,
         interrupt_manager: Arc<dyn InterruptManager<GroupConfig = MsiIrqGroupConfig>>,
         vm: Arc<dyn hypervisor::Vm>,
     ) -> Result<Aia> {

devices/src/gic.rs

@@ -39,7 +39,7 @@ pub struct Gic {
 
 impl Gic {
     pub fn new(
-        vcpu_count: u8,
+        vcpu_count: u32,
         interrupt_manager: Arc<dyn InterruptManager<GroupConfig = MsiIrqGroupConfig>>,
         vm: Arc<dyn hypervisor::Vm>,
     ) -> Result<Gic> {