flash Kinetis: remove TARGET_HALTED halted check from probe

There is no reason why not probe running target.
Initial gdb connect to running target is now possible without
halt in gdb-attach event.

Change-Id: Iacc4a231587d378168b18db871582f1086504831
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/3382


Tested-by: jenkins
Reviewed-by: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>