libbpf-tools/biosnoop: Fix incorrect sizeof in bpf_get_current_comm

sizeof(&piddata.comm) returns the size of the pointer (8 bytes on 64-bit),
while sizeof(piddata.comm) returns the actual size of the char array
(TASK_COMM_LEN). This error caused the task command to be truncated.

Original output (truncated COMM):
TIME(s)     COMM           PID     DISK    T    SECTOR     BYTES   LAT(ms)
0.000634    f2fs_ck        298     mmcblk0 WSM  5037016    16384     0.108
0.004835    kworker        2628    mmcblk0 WFSM 5037048    4096      0.464

Fixed output:
TIME(s)     COMM           PID     DISK    T    SECTOR     BYTES   LAT(ms)
0.000253    f2fs_ckpt-254: 298     mmcblk0 WSM  5032920    20480     0.903
0.002865    kworker/0:0    2628    mmcblk0 WFSM 5032960    4096      0.495

Change-Id: Iaf1753055a9117e3cf6dbbf6dc6a6c753a584f6c
Signed-off-by: Ism Hong <ism.hong@gmail.com>

Author: ismhong

libbpf-tools/biosnoop.bpf.c

@@ -62,7 +62,7 @@ int trace_pid(struct request *rq)
 	struct piddata piddata = {};
 
 	piddata.pid = id >> 32;
-	bpf_get_current_comm(&piddata.comm, sizeof(&piddata.comm));
+	bpf_get_current_comm(&piddata.comm, sizeof(piddata.comm));
 	bpf_map_update_elem(&infobyreq, &rq, &piddata, 0);
 	return 0;
 }