GPU: detects PCIe speed only in driverSpecific mode

Fixes #2419

src/detection/gpu/gpu.h

@@ -64,6 +64,9 @@ typedef struct FFGPUResult {
     uint64_t deviceId;
 } FFGPUResult;
 
+static_assert(sizeof(((FFGPUResult*) NULL)->pcieSpeed) == 8, "pcieSpeed is not 8 bytes");
+static_assert(sizeof(((FFGPUResult*) NULL)->psMax) == 4, "psMax has padding");
+
 const char* ffDetectGPU(const FFGPUOptions* options, FFlist* result);
 const char* ffDetectGPUImpl(const FFGPUOptions* options, FFlist* gpus);