Starting version 23.2.0 of the Support Library you can call
setHintEnabled(false)
or putting it in your TextInputLayout xml as such :
app:hintEnabled="false"
Though the name might makes you think it removes all hints, it just removes the floating one.
Related docs and issue: http://developer.android.com/reference/android/support/design/widget/TextInputLayout.html#setHintEnabled(boolean)
https://code.google.com/p/android/issues/detail?id=181590