Fix stack buffer overflow in ih264d_process_intra_mb

Aligned the sizes of au1_ngbr_pels to ensure SSE42 functions do not
result in stack buffer overflow

Bug: 36490809

Change-Id: I0bfe493f94647046013759b3ec9db3c627ac471e
(cherry picked from commit f69e34419b267be7285a7e0e85a019294118ae03)
1 file changed