ARM: dts: bcm2711: fix MDIO #address- and #size-cells

ARM: dts: bcm2711: fix MDIO #address- and #size-cells

The values of #address-cells and #size-cells are swapped. Fix this
and avoid the following DT schema warnings for mdio@e14:

 #address-cells:0:0: 1 was expected
 #size-cells:0:0: 0 was expected

Fixes: be8af7a9e3cc ("ARM: dts: bcm2711-rpi-4: Enable GENET support")
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/1628334401-6577-2-git-send-email-stefan.wahren@i2se.com
Signed-off-by: Nicolas Saenz Julienne <nsaenz@kernel.org>