[MIPS] Support for several more SNI RM models.

arch/mips/Kconfig

arch/mips/pci/fixup-sni.c

arch/mips/pci/ops-sni.c

arch/mips/sni/Makefile

arch/mips/sni/a20r.c

arch/mips/sni/ds1216.c

arch/mips/sni/irq.c

arch/mips/sni/pcimt.c

arch/mips/sni/pcit.c

arch/mips/sni/reset.c

arch/mips/sni/rm200.c

arch/mips/sni/setup.c

arch/mips/sni/sniprom.c

arch/mips/sni/time.c

include/asm-mips/ds1216.h

include/asm-mips/mach-rm/cpu-feature-overrides.h

include/asm-mips/sni.h