[platforms/drm] Align plane type enum with kernel

This is just a code cosmetic change to have the same values internally like the
kernel for the type enum. In the logic there should not be a difference since
the enum values are mapped at runtime.

plugins/platforms/drm/drm_object_plane.cpp

@@ -83,9 +83,9 @@ bool DrmPlane::initProps()
     });
 
     QVector<QByteArray> typeNames = {
-        QByteArrayLiteral("Primary"),
-        QByteArrayLiteral("Cursor"),
         QByteArrayLiteral("Overlay"),
+        QByteArrayLiteral("Primary"),
+        QByteArrayLiteral("Cursor")
     };
 
     const QVector<QByteArray> rotationNames{

plugins/platforms/drm/drm_object_plane.h

@@ -52,9 +52,9 @@ public:
     };
 
     enum class TypeIndex {
-        Primary = 0,
+        Overlay = 0,
+        Primary,
         Cursor,
-        Overlay,
         Count
     };