Sanitize enableGetChoices from ReferenceInput child component

[ZachSelindh]

When using a SelectInput as a child of a ReferenceInput, and using the prop "enableGetChoices" to prevent an initial call for options, a type error will be thrown:

Warning: React does not recognize the `enableGetChoices` prop on a DOM element.

This PR sanitizes enableGetChoices on ReferenceInput's extant rest props sanitize function.

[djhi]

Thanks!