bug(input-demo): remove align input binding

[BaimosTechnologies]

Bug, feature request, or proposal:

Caused by #5141

I think the .demo-text-align-end class breaks the .mat-input-underline text-align, which causes the underline to align to the end instead to left, see instances below taken from input demo page:

What is the expected behavior?

The underline should be aligned to the left

What is the current behavior?

The underline is aligned at the end

What are the steps to reproduce?

Build the material project, navigate to input-demo.html and focus in the input fields in the images above.

What is the use-case or motivation for changing an existing behavior?

Input demo page should not have this error anymore.

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

2.0.0-beta7

Is there anything else we should know?

Also commented on the pull request #5141, nobody answered so I opened this new issue.

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