Support dynamical input size and shape for TrOcr input image
# 🚀 Feature request

Support dynamical input size and shape for TrOcr input image.

## Motivation

TrOcr has input shape for image 384x384, but can recognise only single line. So It does not effective utilize resources.


This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.