nwfilter: Convert to virMacAddrPtr not virMacAddrPtr*

My previous patch wasn't complete as it converted from
(unsigned char *) to (virMacAddrPtr *). It should be
(virMacAddrPtr) only.

src/nwfilter/nwfilter_dhcpsnoop.c

@@ -2200,7 +2200,7 @@ virNWFilterDHCPSnoopReq(virNWFilterTechDriverPtr techdriver ATTRIBUTE_UNUSED,
                         const char *linkdev ATTRIBUTE_UNUSED,
                         enum virDomainNetType nettype ATTRIBUTE_UNUSED,
                         const unsigned char *vmuuid ATTRIBUTE_UNUSED,
-                        const virMacAddrPtr *macaddr ATTRIBUTE_UNUSED,
+                        const virMacAddrPtr macaddr ATTRIBUTE_UNUSED,
                         const char *filtername ATTRIBUTE_UNUSED,
                         virNWFilterHashTablePtr filterparams ATTRIBUTE_UNUSED,
                         virNWFilterDriverStatePtr driver ATTRIBUTE_UNUSED)