Only set delayed inval for procs using PTI

invltlb_invpcid_pti_handler() was requesting delayed TLB invalidation
even for processes that aren't using PTI. With an out-of-tree
change to avoid PTI for non-jailed root processes, this caused an
assertion failure in pmap_activate_sw_pcid_pti() when context-switching
between PTI and non-PTI processes.

Reviewed by: bdrewery kib tychon
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D29094