net: Initialize all members in skb_gro_remcsum_init()

skb_gro_remcsum_init() initializes the gro_remcsum.delta member only,
leading to compiler warnings about a possibly uninitialized
gro_remcsum.offset member:

drivers/net/vxlan.c: In function ‘vxlan_gro_receive’:
drivers/net/vxlan.c:602: warning: ‘grc.offset’ may be used uninitialized in this function
net/ipv4/fou.c: In function ‘gue_gro_receive’:
net/ipv4/fou.c:262: warning: ‘grc.offset’ may be used uninitialized in this function

While these are harmless for now:
  - skb_gro_remcsum_process() sets offset before changing delta,
  - skb_gro_remcsum_cleanup() checks if delta is non-zero before
    accessing offset,
it's safer to let the initialization function initialize all members.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2342,6 +2342,7 @@ struct gro_remcsum {
 
 static inline void skb_gro_remcsum_init(struct gro_remcsum *grc)
 {
+	grc->offset = 0;
 	grc->delta = 0;
 }