ARM: dts: aspeed: bonnell: Remove MAC3

Bonnell is populated with only one ethernet controller.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20230308222403.1848795-1-eajames@linux.ibm.com


Signed-off-by: Joel Stanley <joel@jms.id.au>