libipt: pip in psb+

Paging events inside PSB+ are asynchronous since the IP is not obvious
from the disassembly.

Turn paging events into async paging events when processing PSB events.

Change-Id: I81c11d68b1168cb0aaad92f6e1af4af0b95daa27
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>