[chore] fix cargo build warnings

Author: equation314

platforms/axplat-aarch64-bsta1000b/src/mp.rs

@@ -8,7 +8,7 @@ pub fn start_secondary_cpu(cpu_id: usize, stack_top: PhysAddr) {
         return;
     }
 
-    let entry = virt_to_phys(va!(crate::boot::_start_secondary as usize));
+    let entry = virt_to_phys(va!(crate::boot::_start_secondary as *const () as usize));
     axplat_aarch64_peripherals::psci::cpu_on(
         CPU_ID_LIST[cpu_id],
         entry.as_usize(),

platforms/axplat-aarch64-phytium-pi/src/power.rs

@@ -14,7 +14,7 @@ impl PowerIf for PowerImpl {
         use crate::config::plat::CPU_ID_LIST;
         use axplat::mem::{va, virt_to_phys};
 
-        let entry = virt_to_phys(va!(crate::boot::_start_secondary as usize));
+        let entry = virt_to_phys(va!(crate::boot::_start_secondary as *const () as usize));
         axplat_aarch64_peripherals::psci::cpu_on(
             CPU_ID_LIST[cpu_id],
             entry.as_usize(),

platforms/axplat-aarch64-qemu-virt/src/power.rs

@@ -12,7 +12,7 @@ impl PowerIf for PowerImpl {
     #[cfg(feature = "smp")]
     fn cpu_boot(cpu_id: usize, stack_top_paddr: usize) {
         use axplat::mem::{va, virt_to_phys};
-        let entry_paddr = virt_to_phys(va!(crate::boot::_start_secondary as usize));
+        let entry_paddr = virt_to_phys(va!(crate::boot::_start_secondary as *const () as usize));
         axplat_aarch64_peripherals::psci::cpu_on(cpu_id, entry_paddr.as_usize(), stack_top_paddr);
     }
 

platforms/axplat-loongarch64-qemu-virt/src/mp.rs

@@ -16,6 +16,6 @@ pub fn start_secondary_cpu(cpu_id: usize, stack_top: PhysAddr) {
     unsafe {
         SMP_BOOT_STACK_TOP = stack_top_virt_addr;
     }
-    csr_mail_send(_start_secondary as usize as _, cpu_id, 0);
+    csr_mail_send(_start_secondary as *const () as _, cpu_id, 0);
     send_ipi_single(cpu_id, ACTION_BOOT_CPU);
 }

platforms/axplat-riscv64-qemu-virt/src/power.rs

@@ -19,7 +19,7 @@ impl PowerIf for PowerImpl {
             warn!("HSM SBI extension is not supported for current SEE.");
             return;
         }
-        let entry = virt_to_phys(va!(_start_secondary as usize));
+        let entry = virt_to_phys(va!(_start_secondary as *const () as usize));
         sbi_rt::hart_start(cpu_id, entry.as_usize(), stack_top_paddr);
     }