Add the I3C documentation describing the protocol, the master driver API and the device driver API. Change-Id: I474f18bf8f904bb469ab10be482927927f8d16c7 Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Git-commit: bd360e8175f4e07418a8427786dfaf9d42867e71 Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git Signed-off-by: Alok Chauhan <alokc@codeaurora.org>