LoongArch: Adjust memory management for 32BIT/64BIT

LoongArch: Adjust memory management for 32BIT/64BIT

Adjust memory management for both 32BIT and 64BIT, including: address
space definition, DMW CSR definition, page table bits definition, boot
time detection of VA/PA bits, page table init, tlb exception handling,
copy_page/clear_page/dump_tlb libraries, etc.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Yawei Li <liyawei@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>