Interpretation of the ccws to register (configuration) indicators contained
a thinko: We want to disallow reading from 0, but setting the indicator
pointer to 0 is fine.
Let's fix the handling for CCW_CMD_SET{,_CONF}_IND.
Cc: qemu-stable@nongnu.org
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>