cfg: support calling legacy stm32 scripts

For the time being we support the old stm32 script names - this will
be removed before the next release cycle.

Signed-off-by: Spencer Oliver <ntfreak@users.sourceforge.net>

tcl/target/stm32.cfg

@@ -0,0 +1,3 @@
+# deprecated cfg file
+echo "DEPRECATED! use script 'target/stm32f1x.cfg' not 'target/stm32.cfg'"
+source [find target/stm32f1x.cfg]

tcl/target/stm32f2xxx.cfg

@@ -0,0 +1,3 @@
+# deprecated cfg file
+echo "DEPRECATED! use script 'target/stm32f2x.cfg' not 'target/stm32f2xxx.cfg'"
+source [find target/stm32f2x.cfg]