I would say no. I can think of at least two reasons:
Touch devices keyboards can be hidden easily.
Imagine the user hides his keyboard after completing the form, how will he know that the submit button he needs is the "enter" keyboard button?
To me it is also frustrating when this action is associated to the "enter" button. In some apps while I'm typing and I want the content to be in a new line I tap this button, which results in the form being sent.
The action of submitting belongs to the Site UI, and needs to be separated from the one of entering content which belongs to the keyboard. And so I don't expect this button to have the submit action (even if I had the keyboard opened).
I just checked that Stack Exchange app uses this functionality, but I still think I would not remove a submit UI button (although you use the keyboard one). My second point has more to do with textareas than with one line inputs, though.