Don't depend on vbios_version sysfs file

On APU's vbios_version string might not be exposed. Relying on vendor ID
to detect AMDGPU is sufficient

Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Change-Id: I08ef4b4bc7491a40f318791803aeaf261f7fac25

src/rocm_smi_main.cc

@@ -543,15 +543,10 @@ 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);