Fix vnic fallback PHY name matching after r334880.

In some cases it seems that the PHY mode can only be identified by
matching against the corresponding device node name in the FDT. r334880
broke this for the case where the node name contains a unit address.
Fix the problem by allowing a match in that case.

Reviewed by: andrew, sbruno
Tested by: sbruno
Differential Revision: https://reviews.freebsd.org/D16259