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/configs/am57xx_hs_evm_defconfig b/configs/am57xx_hs_evm_defconfig
index f7efa2b..743f82c 100644
--- a/configs/am57xx_hs_evm_defconfig
+++ b/configs/am57xx_hs_evm_defconfig
@@ -1,6 +1,7 @@
 CONFIG_ARM=y
-CONFIG_OMAP54XX=y
+CONFIG_ARCH_OMAP2PLUS=y
 CONFIG_SYS_MALLOC_F_LEN=0x2000
+CONFIG_OMAP54XX=y
 CONFIG_TI_SECURE_DEVICE=y
 CONFIG_TARGET_AM57XX_EVM=y
 CONFIG_TI_SECURE_EMIF_REGION_START=0xbdb00000