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/bpf_helpers.h b/samples/bpf/bpf_helpers.h
index 90f44bd..dadd516 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -113,7 +113,7 @@
 #define PT_REGS_FP(x) ((x)->gprs[11]) /* Works only with CONFIG_FRAME_POINTER */
 #define PT_REGS_RC(x) ((x)->gprs[2])
 #define PT_REGS_SP(x) ((x)->gprs[15])
-#define PT_REGS_IP(x) ((x)->ip)
+#define PT_REGS_IP(x) ((x)->psw.addr)
 
 #elif defined(__aarch64__)