first attempt at porting libopencm3 to energymicro

unless sources are explicitly given, the linker scripts and make files
were copied over from the stm32/f1 port.

lib/efm32/tinygecko/EFM32TG840F32.ld

@@ -0,0 +1,15 @@
+/* lengths from d011_efm32tg840_datasheet.pdf table 1.1, offset from
+ * d0034_efm32tg_reference_manual.pdf figure 5.2.
+ *
+ * the origins and memory structure are constant over all tinygeckos, but the
+ * MEMORY section requires the use of constants, and has thus to be duplicated
+ * over the chip variants.
+ * */
+
+MEMORY
+{
+	rom (rx) : ORIGIN = 0, LENGTH = 32k
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 4k
+}
+
+INCLUDE tinygecko.ld;