ARM: omap2+: rename config to ARCH_OMAP2PLUS and consolidate Kconfig

In Linux, CONFIG_ARCH_OMAP2PLUS is used for OMAP2 or later SoCs.
Rename CONFIG_ARCH_OMAP2 to CONFIG_ARCH_OMAP2PLUS to follow this
naming.

Move the OMAP2+ board/SoC choice down to mach-omap2/Kconfig to slim
down the arch/arm/Kconfig level.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/config.mk b/arch/arm/config.mk
index eb09b0e..2143633 100644
--- a/arch/arm/config.mk
+++ b/arch/arm/config.mk
@@ -6,7 +6,7 @@
 #
 
 ifndef CONFIG_STANDALONE_LOAD_ADDR
-ifneq ($(CONFIG_ARCH_OMAP2),)
+ifneq ($(CONFIG_ARCH_OMAP2PLUS),)
 CONFIG_STANDALONE_LOAD_ADDR = 0x80300000
 else
 CONFIG_STANDALONE_LOAD_ADDR = 0xc100000