s390/fs3270: fix function prototypes

fix function prototypes split over two lines like:

static void
foobar(void)

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>