s390/fs3270: add missing braces to if/else

Fix a few missing braces and wrong placement of braces
reported by checkpatch.

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>