PPC: Fix dcbz for linux-user on 970

The default with linux-user for dcbz on 970 is to emulate 32 byte clears.
However, redoing the dcbzl support we added a check to not honor the bit
in HID5 that sets this.

Remove the #ifdef check on linux user, so that we get 32 byte clears again.

Reported-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Alexander Graf <agraf@suse.de>
