physical: Fix readability-braces-around-statements

```
/home/andrew/src/openbmc/phosphor-led-sysfs/build/../physical.cpp:135:25: error: statement should be inside braces [readability-braces-around-statements,-warnings-as-errors]
    if (!color.length())
                        ^
                         {
```

Change-Id: I7ac2e39c4a1b32e08df0161adfb305c25b968873
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
1 file changed