Fixes a number of minor MIPS core attachment issues based on conversation with
mizhka.
Issues fixed:
- Fixed incorrect MIPS74k vendor ID in the bhnd core descriptor tables
- Improved MIPS3302 device description
- Set the bhnd nexus drivers' bus pass to allow early probing of the CPU core.
- Fix MIPS core driver's matching against MIPS/MIPS33 cores.
- Disabled matching the MIPS core driver on non-SoC devices
- Enabled BUS_PASS_CPU on the MIPS core driver ensure correct attach order.