Add st25dvdiscovery driver (#1)

* Add sendCmd(), doTurnOn(), doTurnOff()

* Override all virtual DisplayImpl methods

* Include ST25DVDISCOVERY Display driver to Makefile

* Successful GRAM Access

* Write() functionality

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Co-authored-by: Jay <jdev.coffee@gmail.com>
Signed-off-by: Federico Terraneo <fede.tft@miosix.org>