plat: xilinx: zynqmp: Build for DDR if SPD is enabled
plat: xilinx: zynqmp: Build for DDR if SPD is enabled

This patch builds ATF to DDR if SPD is enabled as it cant fit in
On chip memory(OCM) with SPD enabled. This solves the issue
of build failure with SPD enabled for ZynqMP platform.

Signed-off-by: Siva Durga Prasad Paladugu <673e7ee326f90477823c14a0bc2c27a78ebaa977@xilinx.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware