Provide PRIxBUSADDR, PRIxBUSSIZE, PRIuBUSSIZE, and PRIxBSH for all arches
to follow arm and (generic) mips.

Reviewed by christos.

add bus_addr_t typedef

Fix compilation after bus space changes. They are weak linked to the defaults.

fix build

bus.h is required for build so add some empty file for now.