tcl/target: make sure kex.cfg is not used for Kinetis KE1x families

Config file renamed to ke0x.cfg and a notice added to texi.

While on ke0x.cfg CPUTAPID setting fixed: device has SWD port only, no JTAG.

Removed per device configs as they set CHIPNAME and nothing more.
Let's use reasonably universal chip name 'ke' set in family config.

Change-Id: I313db87a59f25f968eb3c27df155780b67becee8
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/3897


Tested-by: jenkins
Reviewed-by: Ivan Meleca <ivan@artekit.eu>
Reviewed-by: Joakim Nohlgård <joakim.nohlgard@eistec.se>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>