lazy-pages: drop code for page fault message flags processing

The kernel anyways does not really supports any flags for page fault
message and we've used '#if 0' to skip the flags processing. However, we
can just drop this chunk as we anyway will have do some more work than
simply removing '#if 0' to handle UFFD_WP.

travis-ci: success for lazy-pages: add non-#PF events handling (rev2)
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>