[PATCH] xdp: fix type of string pointer in __XDP_ACT_SYM_TAB

["Ben Dooks (Codethink)" <ben.dooks@codethink.co.uk>]

The table entry in __XDP_ACT_SYM_TAB for the last item is set
to { -1, 0 } where it should be { -1, NULL } as the second item
is a pointer to a string.

Fixes the following sparse warnings:

./include/trace/events/xdp.h:28:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:53:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:82:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:140:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:155:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:190:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:225:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:260:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:318:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:356:1: warning: Using plain integer as NULL pointer
./include/trace/events/xdp.h:390:1: warning: Using plain integer as NULL pointer

Signed-off-by: Ben Dooks (Codethink) <ben.dooks@codethink.co.uk>
---
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: netdev@vger.kernel.org
Cc: bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 include/trace/events/xdp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index 8c8420230a10..c7e3c9c5bad3 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -22,7 +22,7 @@
 #define __XDP_ACT_SYM_FN(x)	\
 	{ XDP_##x, #x },
 #define __XDP_ACT_SYM_TAB	\
-	__XDP_ACT_MAP(__XDP_ACT_SYM_FN) { -1, 0 }
+	__XDP_ACT_MAP(__XDP_ACT_SYM_FN) { -1, NULL }
 __XDP_ACT_MAP(__XDP_ACT_TP_FN)
 
 TRACE_EVENT(xdp_exception,
-- 
2.23.0