Hello Neil,
There is not a dedicated Application Note for the i.MX6 Dual Plus power consumption. However, there is an application note (AN5381) in which the current consumption of the i.MX6QP is measured. (Which may help assess the i.MX6DP current consumption). You may find it on the following link:
https://www.nxp.com/docs/en/application-note/AN5381.pdf
It is not as detailed as AN4509 but it should serve as a guidelines for what power consumption to expect when using the i.MX6 Plus variants.
Regards,
