s390/pci_dma: make lazy flush independent from the tlb_refresh bit

We have 2 strategies to reduce the number of RPCIT instructions:
* A HW feature indicated via the tlb_refresh bit allows us to omit RPCIT for
  invalid -> valid translation-table entry updates.
* With "lazy flush" we omit RPCIT for valid -> invalid updates until we run
  out of dma addresses. When we have to reuse dma addresses we issue a global
  tlb flush using only one RPCIT instruction.

Currently lazy flushing depends on tlb_refresh. Since there is no technical
reason for this remove this dependency.

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>