Fix a crash when running amd-smi version --cpu

When running on a system that doesn't support HSMP (such as an APU)
then the following is observed:
```
/usr/include/c++/15.1.1/bits/stl_vector.h:1263: std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = void*; _Alloc = std::allocator<void*>; reference = void*&; size_type = long unsigned int]: Assertion '__n < this->size()' failed.
```

This is because no "CPU" are detected on the SOC, which really means
no CPUs that support HSMP.  Catch this case so that a clean return
can be passed up.

Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

src/amd_smi/amd_smi.cc

@@ -6309,6 +6309,8 @@ amdsmi_status_t amdsmi_get_cpu_handles(uint32_t *cpu_count,
                                                       nullptr, &cpu_per_soc);
         if (status != AMDSMI_STATUS_SUCCESS)
             return status;
+        if (cpu_per_soc == 0)
+            continue;
 
         // Allocate the memory for the cpus
         std::vector<amdsmi_processor_handle> plist(cpu_per_soc);