This reverts commit 2076011e0c. The
comment which explains EINVAL should be expected for this case was
wrong, not the code. The kernel will return ENOTSUP when attaching
a distributed spare to the wrong top-level dRAID vdev. See the
check for this in spa_vdev_attach().
Reviewed-by: Paul Dagnelie <paul.dagnelie@klarasystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#17503