selftests/bpf: Test jited inline of bpf_get_current_task() for LoongArch

selftests/bpf: Test jited inline of bpf_get_current_task() for LoongArch

Add the jited inline instruction of bpf_get_current_task() for LoongArch
to pass the test case.

Before:

  $ sudo ./test_progs -t verifier_jit_inline
  #604/1   verifier_jit_inline/inline_bpf_get_current_task:SKIP
  #604     verifier_jit_inline:SKIP
  Summary: 1/0 PASSED, 1 SKIPPED, 0 FAILED

After:

  $ sudo ./test_progs -t verifier_jit_inline
  #604/1   verifier_jit_inline/inline_bpf_get_current_task:OK
  #604     verifier_jit_inline:OK
  Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>