[SYCL][ROCm] Fix rocm_piPlatformsGet when there are no devices (#4314)

hipGetDeviceCount returns the hipErrorNoDevice error when there are no
available devices. Instead of treating it as a PI error, we now properly
report that the platform is not available.

Author: al42and

sycl/plugins/rocm/pi_rocm.cpp

@@ -696,7 +696,12 @@ pi_result rocm_piPlatformsGet(pi_uint32 num_entries, pi_platform *platforms,
             return;
           }
           int numDevices = 0;
-          err = PI_CHECK_ERROR(hipGetDeviceCount(&numDevices));
+          hipError_t hipErrorCode = hipGetDeviceCount(&numDevices);
+          if (hipErrorCode == hipErrorNoDevice) {
+            numPlatforms = 0;
+            return;
+          }
+          err = PI_CHECK_ERROR(hipErrorCode);
           if (numDevices == 0) {
             numPlatforms = 0;
             return;