AT&T Netgate machine type

Currently, AT&T Netgates are recognized as "net-snmp - Linux" in Orion.  This is due to it being associated with OID "1.3.6.1.4.1.8072.3.2.10" in Orion.  The OID that it should be associated with is "1.3.6.1.4.1.74.1.30" which would have a machine type of "attnetgate".  The OID "1.3.6.1.4.1.74.1.30" is present within Orion as universal pollers can be used against it and it's sub branches.

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