benchmark: Adjust BPF hook point for getpid

On my kernel __x64_sys_getpid() is not available in BTF vmlinux.
The function __do_sys_getpid() is to use that instead.

Tested on kernels:
 - 6.4.10-200.fc38.x86_64
 - 6.5.0-rc5-net-next

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>

benchmark/probes/benchmark.bpf.h

@@ -3,15 +3,15 @@
 #include <bpf/bpf_tracing.h>
 
 #if defined(__TARGET_ARCH_x86)
-#define FENTRY_SEC() SEC("fentry/__x64_sys_getpid")
+#define FENTRY_SEC() SEC("fentry/__do_sys_getpid")
 #elif defined(__TARGET_ARCH_arm64)
 #define FENTRY_SEC() SEC("fentry/__arm64_sys_getpid")
 #else
 #error Unknown target for this architecture
 #endif
 
 #if defined(__TARGET_ARCH_x86)
-#define KPROBE_SEC() SEC("kprobe/__x64_sys_getpid")
+#define KPROBE_SEC() SEC("kprobe/__do_sys_getpid")
 #elif defined(__TARGET_ARCH_arm64)
 #define KPROBE_SEC() SEC("kprobe/__arm64_sys_getpid")
 #else