mcuMemHostRegister: take into account sizeof(float)

cuMemHostRegister expects the size of registered memory in bytes whereas the
memref descriptor in memref_t contains the number of elements.  Get the actual
size in bytes instead.

PiperOrigin-RevId: 257589116

mlir/tools/mlir-cuda-runner/cuda-runtime-wrappers.cpp

@@ -89,8 +89,9 @@ struct memref_t {
 // Allows to register a pointer with the CUDA runtime. Helpful until
 // we have transfer functions implemented.
 extern "C" void mcuMemHostRegister(const memref_t arg, int32_t flags) {
-  reportErrorIfAny(cuMemHostRegister(arg.values, arg.length, flags),
-                   "MemHostRegister");
+  reportErrorIfAny(
+      cuMemHostRegister(arg.values, arg.length * sizeof(float), flags),
+      "MemHostRegister");
 }
 
 /// Prints the given float array to stderr.