[PATCH v2] Add initial mips64 support

Patch adds support for mips64 in makedumpfile. It takes care of vmalloc,
module and directly map kernel memory region's translation. Currently we
only support 3 leverl 16K pages and VA_BITS as 48.

The changes were tested on a mips64 Loongson-3A4000 processor. The dump
compression and filtering (for all dump levels 1,2,4,8,16 and 31) tests
are succussfull.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>