staging: dgap: removes redundant null check and change paramter for dgap_tty_digiseta()

Null checks in dgap_tty_digiseta() are already done by
dgap_tty_ioctl() and change "tty" as a paramter of this function
to "ch" and "bd" which are used in dgap_tty_digiseta().

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/staging/dgap/dgap.c
Simple merge