staging: lustre: ptlrpc: Replace seq_printf() with seq_putc()

Replace seq_printf() with seq_putc() since it is more expensive than
seq_putc().

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>