vmh264: stream mosaic [1/1]

vmh264: stream mosaic [1/1]

PD#SWPL-29711

Problem:
H264 stream mosaic

Solution:
The first gop of the code stream is a single slice,
and the latter part is a multi-slice.
Because the multi-slice detection mechanism is added before,
the single slice decision is triggered by mistake, resulting in mosaic.
Improve multi-slice detection mechanism.

Verify:
u212

Change-Id: I1e3491a1e0441eb50dcec8666c5ebffcd01ba1f7
Signed-off-by: miaohong chen <miaohong.chen@amlogic.com>
(cherry picked from commit 9a5cbbebe1cc6f2b7dff38121ba5a2c9397f6fbf)