arm: zynq: Enable FPGA/FPGA_XILINX via Kconfig

Enabling fpga via Kconfig.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_zc702_defconfig b/configs/zynq_zc702_defconfig
index 54fcbfa..edd8f22 100644
--- a/configs/zynq_zc702_defconfig
+++ b/configs/zynq_zc702_defconfig
@@ -42,6 +42,7 @@
 CONFIG_SPL_DM_SEQ_ALIAS=y
 CONFIG_DFU_MMC=y
 CONFIG_DFU_RAM=y
+CONFIG_FPGA_XILINX=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ZYNQ=y
 CONFIG_SPI_FLASH=y