Newly allocated translation table entries are flagged as invalid
and protected. If an existing translation table entry is invalidated,
the protection flag is left unchanged.

If a page (with invalid and protection flag set) is accessed it's
undefined which type of exception we'll receive.

Make sure to always set the invalid flag only.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>