Include a register that contains SPI controller information. Currently, it only provides the number of slaves addressable by the SPI engine. Original-commit: 1d7d1226e7576bfad484109afd3aad4e78af111b
Original-commit: 14d31c68f0f96d68d81ac248a970a7610c555a6d
Original-commit: 38c549d1f7672e38773fc6624539cc166285a1df