Fix some modules to export more used symbols(cherry picked from commit 5bb3134a8c21cb87b30e135ef168483f0333dabb)
Add opt_platform.h for several modules that have #ifdef FDT in the source.Submitted by: Andre Albsmeier <[email protected]>
Add ofw_bus_if.h to SRCS.
Add modules/spi as a gathering point for SPI-related modules, analagous tomodules/i2c for i2c/iicbus modules. Build spibus as a module.