s390/fs3270: split header files

In order to use the fs3270 one would need at least the ioctl definitions
in uapi. Add two new include files in uapi, which contain:

fs3270: ioctl number declarations + returned struct for TUBGETMOD.
raw3270: all the orders, attributes and similar stuff used with 3270
terminals.

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>