checkseapp: update error message output

Change the final error message to be consistent with the others.

From:
Error: reading /home/wcrobert/workspace/aosp/external/sepolicy/seapp_contexts, line 82, name domain, value system_server

To:
Error: Reading file: "/home/wcrobert/workspace/aosp/external/sepolicy/seapp_contexts" line: 82 name: "domain" value: "system_server"

(cherry picked from commit efebf97e)

Change-Id: Idf791d28fbba95fbeed8b9ccec9a296eea33afb9
Signed-off-by: William Roberts <william.c.roberts@intel.com>