netpoll: avoid put_unaligned() on single character

With a planned cleanup, using put_unaligned() on a single character
results in a harmless warning:

In file included from ./arch/x86/include/generated/asm/unaligned.h:1,
                 from include/linux/etherdevice.h:24,
                 from net/core/netpoll.c:18:
net/core/netpoll.c: In function 'netpoll_send_udp':
include/asm-generic/unaligned.h:23:9: error: 'packed' attribute ignored for field of type 'unsigned char' [-Werror=attributes]
net/core/netpoll.c:431:3: note: in expansion of macro 'put_unaligned'
  431 |   put_unaligned(0x60, (unsigned char *)ip6h);
      |   ^~~~~~~~~~~~~
include/asm-generic/unaligned.h:23:9: error: 'packed' attribute ignored for field of type 'unsigned char' [-Werror=attributes]
net/core/netpoll.c:459:3: note: in expansion of macro 'put_unaligned'
  459 |   put_unaligned(0x45, (unsigned char *)iph);
      |   ^~~~~~~~~~~~~

Replace this with an open-coded pointer dereference.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net/core/netpoll.c

@@ -428,7 +428,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		ip6h = ipv6_hdr(skb);
 
 		/* ip6h->version = 6; ip6h->priority = 0; */
-		put_unaligned(0x60, (unsigned char *)ip6h);
+		*(unsigned char *)ip6h = 0x60;
 		ip6h->flow_lbl[0] = 0;
 		ip6h->flow_lbl[1] = 0;
 		ip6h->flow_lbl[2] = 0;
@@ -456,7 +456,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		iph = ip_hdr(skb);
 
 		/* iph->version = 4; iph->ihl = 5; */
-		put_unaligned(0x45, (unsigned char *)iph);
+		*(unsigned char *)iph = 0x45;
 		iph->tos      = 0;
 		put_unaligned(htons(ip_len), &(iph->tot_len));
 		iph->id       = htons(atomic_inc_return(&ip_ident));