EFIRT on machines with pcid after r337773

If you use UEFI boot, have EFIRT compiled in kernel (the case of
GENERIC) or pre-loaded as module, and efirt is not disabled by a tunable,
and the machine resets during kernel initialization, try this.

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index d5d795ab502..c9334eab916 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
_at__at_ -1188,7 +1188,7 _at__at_ pmap_bootstrap(vm_paddr_t *firstaddr)
 			kernel_pmap->pm_pcids[i].pm_pcid = PMAP_PCID_KERN;
 			kernel_pmap->pm_pcids[i].pm_gen = 1;
 		}
-		PCPU_SET(pcid_next, PMAP_PCID_KERN + 1);
+		PCPU_SET(pcid_next, PMAP_PCID_KERN + 2);
 		PCPU_SET(pcid_gen, 1);
 		/*
 		 * pcpu area for APs is zeroed during AP startup.
_at__at_ -2651,8 +2651,8 _at__at_ pmap_pinit0(pmap_t pmap)
 	bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
 	pmap->pm_flags = pmap_flags;
 	CPU_FOREACH(i) {
-		pmap->pm_pcids[i].pm_pcid = PMAP_PCID_NONE;
-		pmap->pm_pcids[i].pm_gen = 0;
+		pmap->pm_pcids[i].pm_pcid = PMAP_PCID_KERN + 1;
+		pmap->pm_pcids[i].pm_gen = 1;
 		if (!pti) {
 			__pcpu[i].pc_kcr3 = PMAP_NO_CR3;
 			__pcpu[i].pc_ucr3 = PMAP_NO_CR3;