zpool: avoid wrong mount-decoding of dataset

zpool: avoid wrong mount-decoding of dataset

this was mistakenly done as the procfs code uses it and it was
assumed we need to decode this too to get both in the same
encoding-space and thus correct comparission.

But only procfs has that encoding, we don't have it for pool values
in the storage config, so we must not do a decode on that value, that
could potentially break.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>