ARM: new platform for Energy Micro's EFM32 Cortex-M3 SoCs

There are still some missing parts (e.g. board support, device trees),
but with these bits added on top of this patch I can successfully boot a
EFM32GG-DK3750 board that uses an EFM32GG990F1024.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index c99b108..6da9abb 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -153,6 +153,7 @@
 machine-$(CONFIG_ARCH_DAVINCI)		+= davinci
 machine-$(CONFIG_ARCH_DOVE)		+= dove
 machine-$(CONFIG_ARCH_EBSA110)		+= ebsa110
+machine-$(CONFIG_ARCH_EFM32)		+= efm32
 machine-$(CONFIG_ARCH_EP93XX)		+= ep93xx
 machine-$(CONFIG_ARCH_EXYNOS)		+= exynos
 machine-$(CONFIG_ARCH_GEMINI)		+= gemini