bhyve: tests: fix build

Commit b20d39a introduced a new argument for the
virNetDevTapCreateInBridgePort function, however, its mock
in bhyve tests wasn't updated, so the build failed.

Fix build by adding this new argument to the mock version.

tests/bhyvexml2argvmock.c

@@ -22,6 +22,7 @@ int virNetDevTapCreateInBridgePort(const char *brname ATTRIBUTE_UNUSED,
                                    char **ifname,
                                    const virMacAddr *macaddr ATTRIBUTE_UNUSED,
                                    const unsigned char *vmuuid ATTRIBUTE_UNUSED,
+                                   const char *tunpath ATTRIBUTE_UNUSED,
                                    int *tapfd ATTRIBUTE_UNUSED,
                                    int tapfdSize ATTRIBUTE_UNUSED,
                                    virNetDevVPortProfilePtr virtPortProfile ATTRIBUTE_UNUSED,