Panic on aarch64

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

I just got this:

panic: pr_phinpage_check: [vcachepl] item 0xffff000054d19880 not part of pool
cpu0: Begin traceback...
trace fp ffffffc0405efc90
fp ffffffc0405efcb0 vpanic() at ffffffc000240880 netbsd:vpanic+0x160
fp ffffffc0405efd20 panic() at ffffffc000240974 netbsd:panic+0x44
fp ffffffc0405efdb0 pool_cache_put_paddr() at ffffffc00023e858 netbsd:pool_cache_put_paddr+0x110
fp ffffffc0405efde0 vrelel() at ffffffc00028b058 netbsd:vrelel+0x208
fp ffffffc0405efe20 vrecycle() at ffffffc00028b90c netbsd:vrecycle+0x6c
fp ffffffc0405efe50 vdrain_thread() at ffffffc00028bf54 netbsd:vdrain_thread+0x2ac
address 0x100 is invalid
address 0xe8 is invalid
cpu0: End traceback...

I didn't have it set to enter ddb on panic and don't have enough swap
on the eMMC disk to dump to.

Have enabled DDB now.