vdec: fix h264 and h265 jitter problem [1/1]

vdec: fix h264 and h265 jitter problem [1/1]

PD#SWPL-33158

Problem:
During the start of the playback, due to the inconsistent variable type
between poc and loop_playback_poc_threshold, it enters the logic of loop
playback and sets some frames that are not decoded as output, which
causes the number of frames to be less than the number of decoded frames

Solution:
Set the relevant variables of poc to int type.

Verify:
AK301

Change-Id: Ib3a030b373e98c64ac238211b33529816f7eedcd
Signed-off-by: gan.zhang <gan.zhang@amlogic.com>