net/tap: fix memcpy with incorrect size

net/tap: fix memcpy with incorrect size

Fix incorrect sizeof operation being used for getting mac addr size.

Found while compiling with arm64 clang.
drivers/net/tap/rte_eth_tap.c:1410:40: error: argument to 'sizeof' in
    'memcpy' call is the same pointer type 'struct ether_addr *' as the
    destination; expected 'struct ether_addr' or an explicit length
    [-Werror,-Wsizeof-pointer-memaccess]
       rte_memcpy(&pmd->eth_addr, mac_addr, sizeof(mac_addr));
                  ~~~~~~~~~~~~~~            ^~~~~~~~~~~~~~~~

Fixes: bcab6c1d27fa ("net/tap: allow user MAC to be passed as args")

Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Acked-by: Zhiyong Yang <zhiyong.yang@intel.com>