Nucleo-F439ZI support

[pmantoine]

STM Nucleo-F439ZI is identical to the F429ZI with the only difference being that it has crypto hardware in the CPU itself.

As such... it just needs the Nucleo-F429ZI variant and board files copied and appropriately updated with 439 instead of 429 inserted in all the relevant places.

I have done this manually myself... happy to contribute the files if desired.

Note that user can add a STM32 based board following this wiki

Any contribution is welcome, so do not hesitate to submit a PR.

All new variant request will be moved to [New Variant] request list #722 and the related issue will be closed.

[fpistm]

Hi @pmantoine
Feel free to submit a PR.

[pmantoine]

Will do.

[fpistm]

Added to #722.

[pmantoine]

Issued PR as requested, apologies for the delay.