s390/con3270: use msecs_to_jiffies()

Use msecs_to_jiffies() instead of HZ/10.

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>