ARM: integrator: split board select into AP/CP select and CM select

Select integrator boards by the combination of platform select (AP/CP)
and core module select (CM720T, CM920T, ...).

This allows us to remove CONFIG_SYS_EXTRA_OPTIONS and make Kconfig
much cleaner.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
diff --git a/configs/integratorcp_cm946es_defconfig b/configs/integratorcp_cm946es_defconfig
index dcd034d..e7fc706 100644
--- a/configs/integratorcp_cm946es_defconfig
+++ b/configs/integratorcp_cm946es_defconfig
@@ -1,4 +1,4 @@
-CONFIG_SYS_EXTRA_OPTIONS="CM946ES"
 CONFIG_ARM=y
 CONFIG_ARCH_INTEGRATOR=y
-CONFIG_TARGET_INTEGRATORCP_CM946ES=y
+CONFIG_ARCH_INTEGRATOR_CP=y
+CONFIG_CM946ES=y