Replace QGeoMapType argument of cameraCapabilities

Since the only part of QGeoMapType used in the method is mapId, there's
no need to pass the whole map type as argument.
The benefit is that the camera caps can be requested solely based on
the info in QGeoTileSpec.

Change-Id: Iafd0e2a1d4d45fbf02b862efe56841001cbebd75
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>