s390/3270: use diagnose 0x210 for device sensing under z/VM
s390/3270: use diagnose 0x210 for device sensing under z/VM

There is a debugging leftover from git commit 4d334fd155b53adf
"s390/3270: asynchronous size sensing" in raw3270_reset_device_cb.
Under z/VM the diagnose 0x210 can be used to find the correct
size of the 3270 terminal.

Signed-off-by: Martin Schwidefsky <52616596d8f5df0d597e85ab515377f92f939c68@de.ibm.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs