bpf/samples: Fix PT_REGS_IP on s390x and use it

The files "sampleip_kern.c" and "trace_event_kern.c" directly access
"ctx->regs.ip" which is not available on s390x. Fix this and use the
PT_REGS_IP() macro instead.

Also fix the macro for s390x and use "psw.addr" from "pt_regs".

Reported-by: Zvonko Kosic <zvonko.kosic@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/samples/bpf/trace_event_kern.c b/samples/bpf/trace_event_kern.c
index 71a8ed3..41b6115 100644
--- a/samples/bpf/trace_event_kern.c
+++ b/samples/bpf/trace_event_kern.c
@@ -50,7 +50,7 @@ int bpf_prog1(struct bpf_perf_event_data *ctx)
 	key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
 	if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
 		bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
-				 ctx->regs.ip);
+				 PT_REGS_IP(&ctx->regs));
 		return 0;
 	}