Staging: ipack/devices/ipoctal: simplify ipoctal_write_tty()

Remove count_wr and the assigment of nb_bytes = 0 in that function as is
useless. Now it returns the count of the characters actually sent.

There is other nb_bytes = 0 deleted that has a duplicate a few lines before.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>