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/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
index 483c3a0..a4deddf 100644
--- a/arch/arm/mach-zynq/Kconfig
+++ b/arch/arm/mach-zynq/Kconfig
@@ -14,7 +14,16 @@
 	bool "Zynq PicoZed"
 
 config TARGET_ZYNQ_ZC70X
-	bool "Zynq ZC702/ZC706 Board"
+	bool "Zynq ZC702/ZC706 Board (deprecated)"
+	help
+	  This option is deprecated.  Use TARGET_ZYNQ_ZC702
+	  or TARGET_ZYNQ_706.
+
+config TARGET_ZYNQ_ZC702
+	bool "Zynq ZC702 Board"
+
+config TARGET_ZYNQ_ZC706
+	bool "Zynq ZC706 Board"
 
 config TARGET_ZYNQ_ZC770
 	bool "Zynq ZC770 Board"
@@ -37,7 +46,8 @@
 	default "zynq_zed" if TARGET_ZYNQ_ZED
 	default "zynq_microzed" if TARGET_ZYNQ_MICROZED
 	default "zynq_picozed" if TARGET_ZYNQ_PICOZED
-	default "zynq_zc70x" if TARGET_ZYNQ_ZC70X
+	default "zynq_zc70x" if TARGET_ZYNQ_ZC702 || TARGET_ZYNQ_ZC706 \
+			        || TARGET_ZYNQ_ZC70X
 	default "zynq_zc770" if TARGET_ZYNQ_ZC770
 	default "zynq_zybo" if TARGET_ZYNQ_ZYBO