s390/tty3270: move resize work to raw3270

This change was initially made to reduce code duplication when the
con3270 and tty3270 shared the same resize code. It still makes sense
to move the resize workqueue to raw3270 in case we add some other view
later.

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