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/dra7xx_evm_defconfig b/configs/dra7xx_evm_defconfig
index 4582cf0..462e6ff 100644
--- a/configs/dra7xx_evm_defconfig
+++ b/configs/dra7xx_evm_defconfig
@@ -1,8 +1,9 @@
 CONFIG_ARM=y
-CONFIG_OMAP54XX=y
+CONFIG_ARCH_OMAP2PLUS=y
 CONFIG_SYS_MALLOC_F_LEN=0x2000
-# CONFIG_SPL_NAND_SUPPORT is not set
+CONFIG_OMAP54XX=y
 CONFIG_TARGET_DRA7XX_EVM=y
+# CONFIG_SPL_NAND_SUPPORT is not set
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_ARMV7_LPAE=y