ksmbd: Fix buffer_check_err() kernel-doc comment

Add the description of @rsp_org in buffer_check_err() kernel-doc comment
to remove a warning found by running scripts/kernel-doc, which is caused
by using 'make W=1'.
fs/ksmbd/smb2pdu.c:4028: warning: Function parameter or member 'rsp_org'
not described in 'buffer_check_err'

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Fixes: cb451720

 ("ksmbd: remove smb2_buf_length in smb2_hdr")
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Steve French <stfrench@microsoft.com>