test: physical: Fix cppcoreguidelines-special-member-functions

```
../test/physical.cpp:44:7: error: class 'MockLed' defines a non-default destructor but does not define a copy constructor, a copy assignment operator, a move constructor or a move assignment operator [cppcoreguidelines-special-member-functions,-warnings-as-errors]
class MockLed : public phosphor::led::SysfsLed
      ^
```

Change-Id: I8f13a36b826a9661377222dbd4b8a84fcbcdf23a
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
1 file changed