When using Slim Bootloader the UART configuration isn't quite the same
as with the UEFI BIOS. In particular, UART2 is hidden in PCIe and is
instead accessible using a fixed MMIO address. Interrupts are also not
supported for this UART currently.
The simplest way to create builds against this special BIOS/bootloader
setup seems to be to create a new board variant/definition which lets
us provide a custom device tree overlay as well a dedicated Kconfig
default configuration.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Tomasz Bursztyka