Add sepolicy for gralloc-alloc HAL

Allow SurfaceFlinger to call into IAllocator, and allow everyone to access
IAllocator's fd.

Specifically,

hwbinder_use(...) for
avc: denied { call } for scontext=u:r:hal_graphics_allocator:s0 tcontext=u:r:hwservicemanager:s0 tclass=binder permissive=1
avc: denied { transfer } for scontext=u:r:hal_graphics_allocator:s0 tcontext=u:r:hwservicemanager:s0 tclass=binder permissive=1

allow ... ion_device:chr_file r_file_perms for
avc: denied { read } for name="ion" dev="tmpfs" ino=15014 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:ion_device:s0 tclass=chr_file permissive=1
avc: denied { open } for path="/dev/ion" dev="tmpfs" ino=15014 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:ion_device:s0 tclass=chr_file permissive=1
avc: denied { ioctl } for path="/dev/ion" dev="tmpfs" ino=15014 ioctlcmd=4900 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:ion_device:s0 tclass=chr_file permissive=1

allow ... gpu_device:chr_file rw_file_perms; for
avc: denied { read write } for name="kgsl-3d0" dev="tmpfs" ino=14956 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:gpu_device:s0 tclass=chr_file permissive=1
avc: denied { open } for path="/dev/kgsl-3d0" dev="tmpfs" ino=14956 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:gpu_device:s0 tclass=chr_file permissive=1
avc: denied { ioctl } for path="/dev/kgsl-3d0" dev="tmpfs" ino=14956 ioctlcmd=940 scontext=u:r:hal_graphics_allocator:s0 tcontext=u:object_r:gpu_device:s0 tclass=chr_file permissive=1

binder_call(surfaceflinger, ...) for
avc: denied { call } for scontext=u:r:surfaceflinger:s0 tcontext=u:r:hal_graphics_allocator:s0 tclass=binder permissive=1

allow ... ...:fd use for
avc: denied { use } for path="anon_inode:dmabuf" dev="anon_inodefs" ino=12794 scontext=u:r:surfaceflinger:s0 tcontext=u:r:hal_graphics_allocator:s0 tclass=fd permissive=1

Bug: 32021161
Test: make bootimage
Change-Id: Ie7700142313407ac438c43dd1a85544dc4c67f13