net: dsa: felix: fix internal MDIO controller resource length

The blamed commit did not properly convert the resource start/end format
into the DEFINE_RES_MEM_NAMED() start/length format, resulting in a
resource for vsc9959_imdio_res which is much longer than expected:

$ cat /proc/iomem
1f8000000-1f815ffff : pcie@1f0000000
  1f8140000-1f815ffff : 0000:00:00.5
    1f8148030-1f815006f : imdio

vs (correct)

$ cat /proc/iomem
1f8000000-1f815ffff : pcie@1f0000000
  1f8140000-1f815ffff : 0000:00:00.5
    1f8148030-1f814803f : imdio

Luckily it's not big enough to exceed the size of the parent resource
(pci_resource_end(pdev, VSC9959_IMDIO_PCI_BAR)), and it doesn't overlap
with anything else that the Linux driver uses currently, so the larger
than expected size isn't a practical problem that I can see. Although it
is clearly wrong in the /proc/iomem output.

Fixes: 044d447a ("net: dsa: felix: use DEFINE_RES_MEM_NAMED for resources")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>