ARM: pm: ensure our temporary page table entry is removed from the TLB

Ensure that our temporary page table entry is flushed from the TLB
before we resume normal operations.  This ensures that userspace
won't trip over the stale TLB entry.

Tested-by: Kevin Hilman <khilman@ti.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>