drivers/staging/dgnc: Added spaces around a bitwise OR.

Coding rules request placing bitwise OR operators between empty spaces
for better readibility. This patch applies this format to a line in
dgnc_tty.c file.

Signed-off-by: Juanma de Hoyos <juanmahv@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>