highbank: kconfig: move common settings

Move Highbank-specific settings to highbank/Kconfig.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Rob Herring <robh@kernel.org>
diff --git a/configs/highbank_defconfig b/configs/highbank_defconfig
index 23fd52d..88efbdf 100644
--- a/configs/highbank_defconfig
+++ b/configs/highbank_defconfig
@@ -1,2 +1,2 @@
 CONFIG_ARM=y
-CONFIG_TARGET_HIGHBANK=y
+CONFIG_ARCH_HIGHBANK=y