The register tests walks all the registers to verify they are initially
0 when appropriate.  However, if the MAC address is set in the register
space, this should not be checked against 0.

Reviewed-by: Hao Wu <wuhaotsh@google.com>
Signed-off-by: Patrick Venture <venture@google.com>
Message-Id: <20220906163138.2831353-1-venture@google.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>