A single character (line break) should be put into a sequence.
Thus use the corresponding function "seq_putc".

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Acked-by: NCharles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>