xilinx: Enable OF_BOARD for zynq and zynqmp boards

The commit 985503439762 ("fdt: Don't call board_fdt_blob_setup() without
OF_BOARD") forced to enable OF_BOARD for platforms which provide DT
externally. Zynq/ZynqMP boards are using this feature for a long time
that's why there is a need to enable it by default.

Also code expects to return error in case of error that's why also fill it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/9f11bbffe2849f4da7d72712082d579262fe8fd8.1645104518.git.michal.simek@xilinx.com
diff --git a/configs/xilinx_zynq_virt_defconfig b/configs/xilinx_zynq_virt_defconfig
index b19a788..5d18045 100644
--- a/configs/xilinx_zynq_virt_defconfig
+++ b/configs/xilinx_zynq_virt_defconfig
@@ -59,6 +59,7 @@
 CONFIG_CMD_MTDPARTS_SPREAD=y
 CONFIG_CMD_MTDPARTS_SHOW_NET_SIZES=y
 CONFIG_CMD_UBI=y
+CONFIG_OF_BOARD=y
 CONFIG_OF_LIST="zynq-zc702 zynq-zc706 zynq-zc770-xm010 zynq-zc770-xm011 zynq-zc770-xm011-x16 zynq-zc770-xm012 zynq-zc770-xm013 zynq-cc108 zynq-microzed zynq-minized zynq-picozed zynq-zed zynq-zturn zynq-zturn-v5 zynq-zybo zynq-zybo-z7 zynq-dlc20-rev1.0"
 CONFIG_ENV_IS_NOWHERE=y
 CONFIG_ENV_IS_IN_FAT=y