Allow receiver to override encryption properties in case of replication

Currently, the receiver fails to override the encryption
property for the plain replicated dataset with the error:
"cannot receive incremental stream: encryption property
'encryption' cannot be set for incremental streams.". The
problem is resolved by allowing the receiver to override
the encryption property for plain replicated send.

Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>