ARM: zynq: add separate configuration for ZC702 and ZC706

Prior to this commit, ZC702 and ZC706 shared the same configuration
and were built as follows:

ZC702: make zynq_zc70x_defconfig && make
ZC706: make zynq_zc70x_defconfig && make DEVICE_TREE=zynq-zc706

This commit introduces separate configuration for them, which makes
the next commit much easier.

Going forward, the recommended build commands are:

ZC702: make zynq_zc702_defconfig && make
ZC706: make zynq_zc706_defconfig && make

Although the old work flow is still supported, CONFIG_TARGET_ZC70X
has been marked as deprecated.  If used, the warning message is
shown to prompt users to switch to the new scheme.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_zc706_defconfig b/configs/zynq_zc706_defconfig
new file mode 100644
index 0000000..4e79713
--- /dev/null
+++ b/configs/zynq_zc706_defconfig
@@ -0,0 +1,10 @@
+CONFIG_ARM=y
+CONFIG_ARCH_ZYNQ=y
+CONFIG_TARGET_ZYNQ_ZC706=y
+CONFIG_DEFAULT_DEVICE_TREE="zynq-zc706"
+# CONFIG_SYS_MALLOC_F is not set
+CONFIG_SPL=y
+CONFIG_FIT=y
+CONFIG_FIT_VERBOSE=y
+CONFIG_FIT_SIGNATURE=y
+CONFIG_OF_CONTROL=y