ptp: ptp_read should not release queue

Firstly, queue is not the memory allocated in ptp_read;
Secondly, other processes may block at ptp_read and wait for conditions to be
met to perform read operations.
Acked-by: Richard Cochran <richardcochran@gmail.com>
Reported-and-tested-by: syzbot+df3f3ef31f60781fa911@syzkaller.appspotmail.com
Fixes: 8f5de6fb ("ptp: support multiple timestamp event readers")
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Link: https://lore.kernel.org/r/tencent_18747D76F1675A3C633772960237544AAA09@qq.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/ptp/ptp_chardev.c

@@ -585,7 +585,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 free_event:
 	kfree(event);
 exit:
-	if (result < 0)
-		ptp_release(pccontext);
 	return result;
 }