selftests/bpf: Fix bpf_iter/task_vma test

selftests/bpf: Fix bpf_iter/task_vma test

For selftest bpf_iter/task_vma, I got a failure like below on my qemu run:

test_task_vma_common:FAIL:compare_output unexpected compare_output:
    actual
    '561593546000-561593585000r--p0000000000:241256579534/root/devshare/bpf-next/tools/testing/selftests/bpf/test_progs'
    != expected
    '561593546000-561593585000r--p0000000000:245551546830/root/devshare/bpf-next/tools/testing/selftests/bpf/test_progs'

Further debugging found out file->f_inode->i_ino value may exceed 32bit,
e.g., i_ino = 0x14c2eae35, but the format string is '%u'. This caused
inode mismatch between bpf iter and proc result.

Fix the issue by using format string '%llu' to accommodate 64bit i_ino.

Fixes: e8168840e16c ("selftests/bpf: Add test for bpf_iter_task_vma")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260610051831.1346659-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>