Move hal_light to attribute.

HAL policy defines how the platform and a given HAL interact, but not how the
HAL is implemented.  This policy should be represented as an attribute that all
processes implementing the HAL can include.

Bug: 32123421
Test: Builds.
Change-Id: I17e5612c0835773c28e14f09e2ce7bdc3f210c15
diff --git a/private/file_contexts b/private/file_contexts
index a341d7e..f1d736d 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -227,7 +227,7 @@
 /system/bin/hw/android\.hardware\.boot@1\.0-service           u:object_r:hal_boot_exec:s0
 /system/bin/hw/android\.hardware\.graphics\.allocator@2\.0-service   u:object_r:hal_graphics_allocator_exec:s0
 /system/bin/hw/android\.hardware\.graphics\.composer@2\.1-service    u:object_r:hal_graphics_composer_exec:s0
-/system/bin/hw/android\.hardware\.light@2\.0-service          u:object_r:hal_light_exec:s0
+/system/bin/hw/android\.hardware\.light@2\.0-service          u:object_r:hal_light_default_exec:s0
 /system/bin/hw/android\.hardware\.memtrack@1\.0-service       u:object_r:hal_memtrack_exec:s0
 /system/bin/hw/android\.hardware\.nfc@1\.0-service            u:object_r:hal_nfc_exec:s0
 /system/bin/hw/android\.hardware\.power@1\.0-service          u:object_r:hal_power_exec:s0