1. On n64, use XKPHYS to map page table pages instead of KSEG0. Maintain
just one freepages list on n64.
The changes are mainly to introduce MIPS_PHYS_TO_DIRECT(pa),
MIPS_DIRECT_TO_PHYS(), which will use KSEG0 in 32 bit compilation
and XKPHYS in 64 bit compilation.
2. Change macro based PMAP_LMEM_MAP1(), PMAP_LMEM_MAP2(), PMAP_LMEM_UNMAP()
to inline functions.
3. Introduce MIPS_DIRECT_MAPPABLE(pa), which will further reduce the cases
in which we will need to have a special case for 64 bit compilation.
4. Update CP0 hazard definitions for CPU_RMI - the cpu does not need any
nops
Reviewed by: neel
8eec5e8f9c