Icon of a recovery partition is automatically created by EFM. How do I disable that?

For example, you can create a file

/etc/hal/fdi/policy/20-ignore-recovery.fdi

with contents

<?xml version="1.0" encoding="UTF-8"?>
<deviceinfo version="0.2">
  <device>
    <match key="volume.label" string="WinRE">
        <merge key="volume.ignore" type="bool">true</merge>
    </match>
  </device>
</deviceinfo>

This forces HAL to ignore a volume with label WinRE. See section  Device Information Files in  HAL Specification for more information.