arm64: zynqmp: Enable DP for kv260-revA board

DP is enabled for revB and should be enabled for kv260-revA too. Changes in
other boards were done by commit 8b82a3a7 ("arm64: zynqmp: Enable DP
driver for SOMs").

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/4e273bce3a8acf4495b67b702b1704acec8d9ccb.1654779436.git.michal.simek@amd.com