orangepi-r2s-usb.wks: remove unused file

[Michael Opdenacker (michaelopdenacker)]

Description

Remove unused file: orangepi-r2s-usb.wks

Checklist

• [x ] I have read and understood the Contributing Changes to a Component and Recipe Style Guide sections in the Yocto Project documentation
• [x ] I have tested this change (provide brief details below)
• Documentation has been added/updated where necessary in the README and docs/
• If the change is to a BSP in
  DEPRECATED.md,
  then it is maintenance-only, i.e. it does not add support for a
  previously-removed BSP (or significant features to one slated for removal)
• (For new/modified BSPs) I have added relevant information in the README table
• (For new/modified BSPs) The bitbake-setup templates in bitbake-registry/
  have been updated, if necessary
• (For new/modified BSPs) A kas file has been provided in kas/
• [ x] I have added my Signed-off-by and any other tags to each commit

How has this been tested?

The change should be innocuous, but tested I could generate an image for OrangePi R2S anyway.

[Khem Raj (kraj)]

removals are always good. Thank you