Fix dsl_props_set_sync_impl to work with nested nvlist

When iterating over the input nvlist in dsl_props_set_sync_impl() when we don't
preserve the nvpair name before looking up ZPROP_VALUE, so when we later go to
process it nvpair_name() is always "value" and not the actual property name.

This fixes a couple of bugs in zfs_ioc_recv():

• Received properties were not restored correctly when failing to receive an

incremental send stream

• Received properties were not completely replaced by the new ones when

successfully receiving an incremental send stream

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #5497