fix(cpu_idle): replace psci_power_down by a WFI call

For physical boards (e.g. ZCU102), when using the Remote IO
there is a problem already identified when the Frontend VM's
CPU goes to the idle state, as a result of the trap process
and MMIO emulation. In this scenario, currently Bao Hypervisor
is unable to save the state of the registers before powering off.
This patch replaces the psci_power_down call by an explicit WFI
(Wait For Interrupt), temporarily resolving the problem.

Signed-off-by: joaopeixoto13 <[email protected]>

src/arch/armv8/armv8-a/cpu.c

@@ -29,7 +29,7 @@ void cpu_arch_profile_init(cpuid_t cpuid, paddr_t load_addr)
 
 void cpu_arch_profile_idle()
 {
-    int64_t err = psci_power_down(PSCI_WAKEUP_IDLE);
+    int64_t err = PSCI_E_NOT_SUPPORTED;
     if (err) {
         switch (err) {
             case PSCI_E_NOT_SUPPORTED: