libselinux: Fix location of product_seapp_contexts

Fixes a mistake made in aosp/851559. Actual location of
product_seapp_contexts is /product/etc/selinux/product_seapp_contexts

Bug: 119305624
Test: dataservice_app is correctly labeled on blueline
Change-Id: Ic25472d44efa57418fb38cf65f9726a7fda2b417
1 file changed