drm/xe: map MMIO BAR according to the num of tiles in device desc

When MMIO BAR is initially mapped, the driver assumes a single tile device.
However, former memory allocations take all tiles into account.
First, a common standard for resource usage is needed here.
Second, with the next (6th) patch in this series, the MMIO BAR remapping
will be done only if a reduced-tile device is attached.

Signed-off-by: Koby Elbaz <kelbaz@habana.ai>
Reviewed-by: Ofir Bitton <obitton@habana.ai>
Reviewed-by: Moti Haimovski <mhaimovski@habana.ai>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>