OpenOCD 0.9.0 added a definition of a single flash bank as
"$_CHIPNAME.flash" (the chip has two flash banks), the new flash bank
definitions are enclosed in catch statements to avoid startup errors.
The original configuration when combined with openocd 0.9.0 caused an
error during flash probing (which happens during GDB connect), because
of three defined flash banks, which made openocd drop the GDB
connection.
Initially supports only Mulles with serial number > 220 (due to missing
MK60DN256ZVLL10 support in k60).
See also: https://github.com/RIOT-OS/RIOT/wiki/Board%3A-Mulle
Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>