rust/vmstate: Fix num_offset in vmstate macros

`num_offset` is a member of `VMStateField`, and there's no need to use
"." to access this field in a `VMStateField` instance.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250318130219.1799170-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed