Fix uninitialized var in hipDeviceGetAttribute (#1497)

This fixes the usage of an uninitialized cdattr variable in hipDeviceGetAttribute for the CUDA backend when taking the switch default, as detailed in #1317.

Note that the directed_tests/runtimeApi/device/hipGetDeviceAttribute.tst test fails for me, but it already did before applying this patch. Let's see what CI says!

hipamd/include/hip/nvcc_detail/hip_runtime_api.h

@@ -992,8 +992,7 @@ inline static hipError_t hipDeviceGetAttribute(int* pi, hipDeviceAttribute_t att
             cdattr = cudaDevAttrEccEnabled;
             break;
         default:
-            cerror = cudaErrorInvalidValue;
-            break;
+            return hipCUDAErrorTohipError(cudaErrorInvalidValue);
     }
 
     cerror = cudaDeviceGetAttribute(pi, cdattr, device);