[S390] dasd_eckd / Write format R0 is now allowed BB

Permission is now granted to the subsystem to format write R0 with:
* an ID = CCHHR, where CC = physical cylinder number,
  HH = physical head number, and R = 0
* a key length of zero
* a data length of eight
* a data field containing all zeros

Signed-off-by: Jean-Baptiste Joret <joret@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>