m68k/mac: Fix SWIM memory resource end address

The resource size is 0x2000 == end - start + 1.
Therefore end == start + 0x2000 - 1.

Cc: Laurent Vivier <lvivier@redhat.com>
Cc: stable@vger.kernel.org # v4.14+
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>