Fix possible 'range start index 16 out of range for slice of length 0'
error by adding a check of the slice data length.
Fixes: f4cf4ae6eb ("rust: Add a new tool called 'pvimg'")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>