time_in_state: Use common BPF helper

The BPF helper is moved into system/bpf/include/ and is available
to all BPF programs in the include search path. Make use of it.

Only minor refactor, no functional change.

Bug: 122665156
Change-Id: I21db3e9fd7063ae2b10833693f74857472217611
Signed-off-by: Joel Fernandes <joelaf@google.com>
diff --git a/test/bpf_load_tp_prog.c b/test/bpf_load_tp_prog.c
index 37bd516..a8b4860 100644
--- a/test/bpf_load_tp_prog.c
+++ b/test/bpf_load_tp_prog.c
@@ -17,7 +17,7 @@
 #include <linux/bpf.h>
 #include <stdbool.h>
 #include <stdint.h>
-#include "../helpers.h"
+#include <bpf_helpers.h>
 
 struct bpf_map_def SEC("maps") cpu_pid = {
         .type = BPF_MAP_TYPE_ARRAY,