Kconfig: Move config IDENT_STRING to Kconfig

Move the config IDENT_STRING to Kconfig and migrate all boards

[sivadur: Migrate zynq boards]
Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
[trini: Update configs, add some default to sunxi Kconfig]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/nas220_defconfig b/configs/nas220_defconfig
index 91e33d0..8a0cc01 100644
--- a/configs/nas220_defconfig
+++ b/configs/nas220_defconfig
@@ -1,6 +1,7 @@
 CONFIG_ARM=y
 CONFIG_KIRKWOOD=y
 CONFIG_TARGET_NAS220=y
+CONFIG_IDENT_STRING="\nNAS 220"
 CONFIG_BOOTDELAY=3
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="nas220> "