decoder: CB1 fix some crash in peek. [1/1]

decoder: CB1 fix some crash in peek. [1/1]

PD#SWPL-58570

Problem:
When fifo is abnormal, the back-end peek to the wrong data crash.

Solution:
Check whether the fifo is abnormal and return empty when abnormal.

Verify:
adt3

Change-Id: Ie84d4bae905094790af13271ad7bdee9f94ff254
Signed-off-by: gan.zhang <gan.zhang@amlogic.com>