hv_netvsc: cleanup netdev feature flags for netvsc

hv_netvsc: cleanup netdev feature flags for netvsc

BugLink: http://bugs.launchpad.net/bugs/1583357
1. Adding NETIF_F_TSO6 feature flag;
2. Adding NETIF_F_HW_CSUM. NETIF_F_IPV6_CSUM and NETIF_F_IP_CSUM are
being deprecated;
3. Cleanup the coding style of flag assignment by using macro.

Signed-off-by: Simon Xiao <sixiao@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(back ported from commit a060679c6b3da17dc9e95d0500f811de118ec901)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
 Conflicts:
	drivers/net/hyperv/netvsc_drv.c

Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>