Ignore AMD integrated GPUs

Detect and ignore integrated GPUs reported by rocm.

gpu/gpu_info.h

@@ -42,6 +42,7 @@ typedef struct mem_info {
   uint64_t total;
   uint64_t free;
   unsigned int count;
+  int igpu_index; // If >= 0, we detected an integrated GPU to ignore
   char *err;  // If non-nill, caller responsible for freeing
 } mem_info_t;