cfg: add stm32f0discovery board config

Change-Id: I4fccdbd4e0a3bc70cd425c910ad1007519098e20
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/570
Reviewed-by: Peter Stuge <peter@stuge.se>
Tested-by: jenkins

tcl/board/stm32f0discovery.cfg

@@ -0,0 +1,6 @@
+# This is an STM32F0 discovery board with a single STM32F051R8T6 chip.
+# http://www.st.com/internet/evalboard/product/253215.jsp
+
+source [find interface/stlink-v2.cfg]
+
+source [find target/stm32f0x_stlink.cfg]