Adds a driver for an FPGA fabric / CoreSPI implementation.
Supports multiple instances, assuming they reside in some base address,
offsettable by a constant value.
- Add defconfig and board specific files
- Create mpfs/common for code which is shared between MPFS boards.
- Add support for GPIO driven EMMCSD mux.
- Move DDR Libero definitions from arch to boards.
Signed-off-by: Jani Paalijarvi <jani.paalijarvi@unikie.com>