samples/bpf: fix a couple of style issues in bpf_load

This commit fixes a few style problems in samples/bpf/bpf_load.c:

 - Magic string use of 'DEBUGFS'
 - Useless zero initialization of a global variable
 - Minor style fix with whitespace
Signed-off-by: NDaniel T. Lee <danieltimlee@gmail.com>
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

samples/bpf/bpf_load.c

@@ -40,7 +40,7 @@ int prog_cnt;
 int prog_array_fd = -1;
 
 struct bpf_map_data map_data[MAX_MAPS];
-int map_data_count = 0;
+int map_data_count;
 
 static int populate_prog_array(const char *event, int prog_fd)
 {
@@ -65,7 +65,7 @@ static int write_kprobe_events(const char *val)
 	else
 		flags = O_WRONLY | O_APPEND;
 
-	fd = open("/sys/kernel/debug/tracing/kprobe_events", flags);
+	fd = open(DEBUGFS "kprobe_events", flags);
 
 	ret = write(fd, val, strlen(val));
 	close(fd);
@@ -490,8 +490,8 @@ static int load_elf_maps_section(struct bpf_map_data *maps, int maps_shndx,
 
 		/* Verify no newer features were requested */
 		if (validate_zero) {
-			addr = (unsigned char*) def + map_sz_copy;
-			end  = (unsigned char*) def + map_sz_elf;
+			addr = (unsigned char *) def + map_sz_copy;
+			end  = (unsigned char *) def + map_sz_elf;
 			for (; addr < end; addr++) {
 				if (*addr != 0) {
 					free(sym);