CI: move xen specific changes out of gem5-arm64-xen.yml

Move the xen specific changes out of gem5-arm64-xen.yml.  This allows
for other xen machines in the CI.  Adding Xen machines for qemuarm and
qemuarm64 allows for more testing, which should be expanded when the Xen
Test Framework in meta-virtualization is expanded to work on arm
machines.

Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -112,7 +112,7 @@ fvp-baser-aemv8r64:
 gem5-arm64:
   extends: .build
 
-gem5-arm64-xen:
+gem5-arm64/xen:
   extends: .build
 
 gem5-atp-arm64:
@@ -145,12 +145,6 @@ n1sdp/armgcc:
 qemu-cortex-a53:
   extends: .build
 
-qemuarm/testimage:
-  extends: .build
-
-qemuarm/clang/testimage:
-  extends: .build
-
 qemuarm64-sbsa:
   extends: .build
 
@@ -166,6 +160,18 @@ qemuarm64-secureboot/clang/musl/testimage:
 qemuarm64-secureboot/musl/testimage:
   extends: .build
 
+qemuarm64/xen:
+  extends: .build
+
+qemuarm/clang/testimage:
+  extends: .build
+
+qemuarm/testimage:
+  extends: .build
+
+qemuarm/xen:
+  extends: .build
+
 qemuarmv5/testimage:
   extends: .build