unbound-dhcp-leases-bridge: Don't overwrite static leases

unbound-dhcp-leases-bridge: Don't overwrite static leases

When we import all static leases, their remark will be used as hostname
(because WTF?) and might be overwritten if the device is not sending any
or even the same hostname.

This patch avoids that static leases will be modified.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Reviewed-by: Bernhard Bitsch <bbitsch@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>