arm64: zynqmp: Setup ENV_SIZE via Kconfig for mini targets

Mini targets are using different ENV_SIZE then standard one that's why
defconfigs should be updated to simplify config files.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/xilinx_zynqmp_mini_nand_defconfig b/configs/xilinx_zynqmp_mini_nand_defconfig
index 4c8c2fc..3117770 100644
--- a/configs/xilinx_zynqmp_mini_nand_defconfig
+++ b/configs/xilinx_zynqmp_mini_nand_defconfig
@@ -2,6 +2,7 @@
 CONFIG_SYS_CONFIG_NAME="xilinx_zynqmp_mini_nand"
 CONFIG_ARCH_ZYNQMP=y
 CONFIG_SYS_TEXT_BASE=0x10000
+CONFIG_ENV_SIZE=0x10000
 # CONFIG_CMD_ZYNQMP is not set
 CONFIG_DEFAULT_DEVICE_TREE="zynqmp-mini-nand"
 CONFIG_ENV_VARS_UBOOT_CONFIG=y