Documentation: Update filesystems/debugfs.txt
Documentation: Update filesystems/debugfs.txt

This patch update the Documentation/filesystems/debugfs.txt
file. The main work is to add the description of the following
functions:
    debugfs_create_atomic_t
    debugfs_create_u32_array
    debugfs_create_devm_seqfile
    debugfs_create_file_size

Signed-off-by: Wang Long <e68b6ff438429ca41648c25d0f54e970cf858504@huawei.com>
Signed-off-by: Jonathan Corbet <b2ce64d5587c02f12e367eac59751145a0660c51@lwn.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs