Adding max-width to resolve #2

SVG images using the `u-inlineBlock` utility were expanding to fit the parent container. This fix incorporates the [suggestion](https://github.com/suitcss/utils-display/issues/2#issue-21204594) from @necolas to address that issue. Tested locally using `test.html` in Canary and no breakages occurred. Recreate error and test fix with the following markup as test case:

```html
<section class="u-nbfc u-paddingAs">
  <div class="Grid-cell u-size1of12 u-sizeFit">
    <img alt="Invalid" class="u-marginAs u-inlineBlock" src="/img-invalid.min.svg">
  </div>
  <div class="Grid-cell u-size11of12 u-paddingLm">
    <header>
      <h1>Invalid</h1>
    </header>
    <dl class="Grid u-marginTm">
      <dt class="Grid-cell u-isHiddenVisually">Value</dt>
      <dd class="Grid-cell">1001010110101</dd>
    </dl>
  </div>
</section>
```