Fixed Memory Overflow Errors

In function impeg2d_dec_p_b_slice, there was no check for num_mbs_left ==
0 after skip_mbs function call. Hence, even though it should have returned
as an error, it goes ahead to decode the frame and writes beyond the
buffer allocated for output. Put a check for the same.

Bug: 38207066
Test: before/after execution of PoC on angler/nyc-mr2-dev
Change-Id: If4b7bea51032bf2fe2edd03f64a68847aa4f6a00
(cherry picked from commit 2df080153464bf57084d68ba3594e199bc140eb4)

decoder/impeg2d_pnb_pic.c

diff --git a/decoder/impeg2d_pnb_pic.c b/decoder/impeg2d_pnb_pic.c
index 5540044..69277e5 100644
--- a/decoder/impeg2d_pnb_pic.c
+++ b/decoder/impeg2d_pnb_pic.c
@@ -510,6 +510,12 @@
 
         if(ret)
             return IMPEG2D_MB_TEX_DECODE_ERR;
+
+        if(0 >= ps_dec->u2_num_mbs_left)
+        {
+            break;
+        }
+
         IMPEG2D_TRACE_MB_START(ps_dec->u2_mb_x, ps_dec->u2_mb_y);
 
         u4_x_dst_offset = u4_frm_offset + (ps_dec->u2_mb_x << 4);