staging: lustre: Change 'seq_printf' to 'seq_puts'

Fixes checkpatch.pl warning: Prefer seq_puts to seq_printf.
This can be done as both have same type of first two arguments in their
function definition.

Signed-off-by: Rehas Sachdeva <aquannie@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>