Restore identification of VDEVs using non-native block size

NAME STATE READ WRITE CKSUM
dsk02 ONLINE 0 0 0

  mirror-0   ONLINE       0     0     0
    ada1s4a  ONLINE       0     0     0
    ada2s4a  ONLINE       0     0     0  block size: 512B configured, 4096B native

Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Toomas Soome <tsoome@me.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed off by: Cy Schubert <cy@FreeBSD.org>
Closes #11088