luci-proto-modemmanager: fix acl regex to support more then 9 modem objects

If a modem is restarted often, the modem manager object number is
increased by one. Currently, the regex is set so that the modem can no
longer be selected if the object number is greater than 9. This change
fixes that.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
[replace wildcard with rule duplication to disallow option injection]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>