In n32 and n64, add support for physical address above 4GB by having
64 bit page table entries and physical addresses. Major changes are:
- param.h: update PTE sizes, masks and shift values to support 64 bit PTEs.
- param.h: remove DELAY(), mips_btop(same as atop), mips_ptob (same as
ptoa), and reformat.
- param.h: remove casting to unsigned long in trunc_page and round_page
since this will be used on physical addresses.
- _types.h: have 64 bit __vm_paddr_t for n32.
- pte.h: update TLB LO0/1 access macros to support 64 bit PTE
- pte.h: assembly macros for PTE operations.
- proc.h: md_upte is now 64 bit for n32 and n64.
- exception.S and swtch.S: use the new PTE macros for PTE operations.
- cpufunc.h: TLB_LO0/1 registers are 64bit for n32 and n64.
- xlr_machdep.c: Add memory segments above 4GB to phys_avail[] as they are
supported now.
Reviewed by: jmallett (earlier version)