Boundary Services MAC address conflicts with Guest Addresses range.

[luqmana]

The fixed MAC we use to logical represent Boundary Services is currently set to:

omicron/illumos-utils/src/opte/mod.rs

Line 46 in eee942f

let mac = MacAddr::from_const([0xa8, 0x40, 0x25, 0xf9, 0x99, 0x99]);

But based on the current MAC address allocation scheme it lies in the Guest Addresses range

omicron/common/src/api/external/mod.rs

Lines 1870 to 1887 in eee942f

	// Guest MAC addresses begin with the Oxide OUI A8:40:25. Further, guest
	// address are constrained to be in the virtual address range
	// A8:40:25:F_:__:__. Even further, the range F0:00:00 - FE:FF:FF is
	// reserved for customer-visible addresses (FF:00:00-FF:FF:FF is for
	// system MAC addresses). See RFD 174 for the discussion of the virtual
	// range, and
	// https://github.com/oxidecomputer/omicron/pull/955#discussion_r856432498
	// for an initial discussion of the customer/system address range split.
	// The system range is further split between FF:00:00-FF:7F:FF for
	// fixed addresses (e.g., the OPTE virtual gateway MAC) and
	// FF:80:00-FF:FF:FF for dynamically allocated addresses (e.g., service
	// vNICs).
	//
	// F0:00:00 - FF:FF:FF Oxide Virtual Address Range
	// F0:00:00 - FE:FF:FF Guest Addresses
	// FF:00:00 - FF:FF:FF System Addresses
	// FF:00:00 - FF:7F:FF Reserved Addresses
	// FF:80:00 - FF:FF:FF Runtime allocatable

In practise I don't think it's really a problem, as the boundary services mac is effectively arbitrary and not used for forwarding or filtering packets, but probably good to update nonetheless.