(MODULES-10039) Use "zpool status -P" on Linux

Use "zpool status -P" instead of "zpool status" on Linux. This allows
usage of e.g. LVs, LUKS-devices etc. with ZOL. Also currently only way
(?) to use an L2ARC ("<dev> [...] cache <l2arc-dev>").

Otherwise result in errors like: Error: zpool disk can't be
changed. should be ["/dev/mapper/cryptdevice cache
/dev/rootvg/l2arc"], currently is ["cryptdevice cache l2arc"] (while
the creation worked!)

Changing the devices to their short names ("cryptdevice" and "l2arc")
will fix the above error, but fails to actually create the zpool (as
there are no "/dev/cryptdevice" and "/dev/l2arc").