Fix default gap style in TspDataProvider

The style key should be 'background-color' and the value should be a
string with format '#rrggbb'.

Signed-off-by: Patrick Tasse <patrick.tasse@ericsson.com>

packages/react-components/src/components/data-providers/tsp-data-provider.ts

@@ -150,7 +150,7 @@ export class TspDataProvider {
         return {
             parentKey: '',
             values: {
-                color: 0xCACACA,
+                'background-color': '#CACACA',
                 height: 1.0
             }
         };