Allow hal_graphics_allocator to access vscaler_heap_device

avc: denied { read } for name="vscaler-secure" dev="tmpfs" \
ino=458 scontext=u:r:hal_graphics_allocator_default:s0 \
tcontext=u:object_r:vscaler_heap_device:s0 \
tclass=chr_file permissive=0

Bug: 199467922
Test: ExoPlayer secure playback
Change-Id: I2b3be9f4f038317eb456a20b33e555e8d5db2678