drivers: allow setting BlueNRG public address

The zephyr bluetooth stack expects the controller to know its public
address, if any. At least for BlueNRG, the public address is forgotten with
every reset/power cycle, so there needs to be a way to set it from within
zephyr. This is accomplished using the `Aci_Hal_Write_Config_Data` HCI
command, as described in PM0237.

Signed-off-by: Armin Brauns <armin.brauns@embedded-solutions.at>