infrastructure: remove staging subdomain route53 zone

This caused a collision with an entry for 'staging' in the
main route53 zone that terraform did not catch and warn about.

The intent was to avoid pulling in the top level zone as its
managed by someone else, but since we ended up just creating
the DNS entry manually let's drop the subdomain zone.

Change-Id: I5e03736b043752874b08a95659f98842dfa00775
diff --git a/infra.tf b/infra.tf
index da19792..ab06c6b 100644
--- a/infra.tf
+++ b/infra.tf
@@ -16,24 +16,7 @@
 # server - not currently managed by Systems terraform
 
 # Staging --------------
-# route53
-resource "aws_route53_zone" "staging_zone" {
-    name = "staging.trustedfirmware.org"
-}
-
-resource "aws_route53_record" "staging-ns" {
-    zone_id = aws_route53_zone.staging_zone.zone_id
-    name = "staging.trustedfirmware.org"
-    type = "NS"
-    ttl = 30
-
-    records = [
-        aws_route53_zone.staging_zone.name_servers.0,
-        aws_route53_zone.staging_zone.name_servers.1,
-        aws_route53_zone.staging_zone.name_servers.2,
-        aws_route53_zone.staging_zone.name_servers.3,
-    ]
-}
+# route53 - handle manually
 
 #servers
 resource "aws_instance" "staging-ci" {
@@ -52,11 +35,3 @@
         Environment = "staging"
     }
 }
-
-resource "aws_route53_record" "ci-staging" {
-    zone_id = aws_route53_zone.staging_zone.zone_id
-    name = "ci"
-    type = "A"
-    ttl     = "60"
-    records = [aws_instance.staging-ci.public_ip]
-}