Make vbios version optional when discover GPU

Not all GPU has the vbios, make vbios_version optional.

Change-Id: Idc00a0c17baccadea8f26b955237c513bb9a14df

rocm_smi/src/rocm_smi_main.cc

@@ -470,15 +470,10 @@ static const uint32_t kAmdGpuId = 0x1002;
 
 static bool isAMDGPU(std::string dev_path) {
   std::string vend_path = dev_path + "/device/vendor";
-  std::string vbios_v_path = dev_path + "/device/vbios_version";
   if (!FileExists(vend_path.c_str())) {
     return false;
   }
 
-  if (!FileExists(vbios_v_path.c_str())) {
-    return false;
-  }
-
   std::ifstream fs;
   fs.open(vend_path);