zynqmp: Remove unnnecessary board config file for dc4

Remove unnecessary board specific config file for DC4
board.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Acked-by: Jagan Teki <jteki@openedev.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>