arm: zynq: Move bootcommand to defconfig

It will cleanup generic config and enable option to change it for every
board.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_picozed_defconfig b/configs/zynq_picozed_defconfig
index c39b2cb..7e4dfdf 100644
--- a/configs/zynq_picozed_defconfig
+++ b/configs/zynq_picozed_defconfig
@@ -3,6 +3,8 @@
 CONFIG_SYS_TEXT_BASE=0x4000000
 CONFIG_SPL_STACK_R_ADDR=0x200000
 CONFIG_DEFAULT_DEVICE_TREE="zynq-picozed"
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="run $modeboot || run distro_bootcmd"
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_SPL=y
 CONFIG_SPL_STACK_R=y