LoongArch: BPF: Implement bpf_addr_space_cast instruction

LoongArch: BPF: Implement bpf_addr_space_cast instruction

LLVM generates bpf_addr_space_cast instruction while translating pointers
between native (zero) address space and __attribute__((address_space(N))).
The addr_space=0 is reserved as bpf_arena address space.

rY = addr_space_cast(rX, 0, 1) is processed by the verifier and converted
to normal 32-bit move: wX = wY

rY = addr_space_cast(rX, 1, 0) has to be converted by JIT.

With this, the following test cases passed:

    $ ./test_progs -a arena_htab,arena_list,arena_strsearch,verifier_arena,verifier_arena_large
    #4/1     arena_htab/arena_htab_llvm:OK
    #4/2     arena_htab/arena_htab_asm:OK
    #4       arena_htab:OK
    #5/1     arena_list/arena_list_1:OK
    #5/2     arena_list/arena_list_1000:OK
    #5       arena_list:OK
    #7/1     arena_strsearch/arena_strsearch:OK
    #7       arena_strsearch:OK
    #507/1   verifier_arena/basic_alloc1:OK
    #507/2   verifier_arena/basic_alloc2:OK
    #507/3   verifier_arena/basic_alloc3:OK
    #507/4   verifier_arena/basic_reserve1:OK
    #507/5   verifier_arena/basic_reserve2:OK
    #507/6   verifier_arena/reserve_twice:OK
    #507/7   verifier_arena/reserve_invalid_region:OK
    #507/8   verifier_arena/iter_maps1:OK
    #507/9   verifier_arena/iter_maps2:OK
    #507/10  verifier_arena/iter_maps3:OK
    #507     verifier_arena:OK
    #508/1   verifier_arena_large/big_alloc1:OK
    #508/2   verifier_arena_large/access_reserved:OK
    #508/3   verifier_arena_large/request_partially_reserved:OK
    #508/4   verifier_arena_large/free_reserved:OK
    #508/5   verifier_arena_large/big_alloc2:OK
    #508     verifier_arena_large:OK
    Summary: 5/20 PASSED, 0 SKIPPED, 0 FAILED

Acked-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Tested-by: Vincent Li <vincent.mc.li@gmail.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>