tcl/target: Add config for TI MSP432P4xx

Tested with TI MSP-EXP432P401R LaunchPad, via both on-board XDS110-ET (swd)
and external J-Link (jtag).

Change-Id: Ic0caa8516a155754b1c88a04acc8d3c511d9a5f7
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-on: http://openocd.zylin.com/3485


Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>