target: stm32l0x: drop swj on swd only target

The STM32L0xx devices support only SWD.

Drop swj support.
Add swd transport.
Remove swd transport from the associated board files.

Change-Id: I5f8fb4344b33f8bdefd67fd86326f4dccb674d92
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/9426
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Ahmed Haoues <ahmed.haoues@st.com>
Tested-by: jenkins

tcl/board/stm32l0discovery.cfg

@@ -5,8 +5,6 @@
 
 source [find interface/stlink.cfg]
 
-transport select swd
-
 set WORKAREASIZE 0x2000
 source [find target/stm32l0.cfg]
 

tcl/target/stm32l0.cfg

@@ -1,11 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 #
-# M0+ devices only have SW-DP, but swj-dp code works, just don't
-# set any jtag related features
+# stm32l0x devices support SWD transports only.
 #
+transport select swd
 
-source [find target/swj-dp.tcl]
 source [find mem_helper.tcl]
 
 if { [info exists CHIPNAME] } {
@@ -38,7 +37,7 @@ if { [info exists CPUTAPID] } {
     set _CPUTAPID 0x0bc11477
 }
 
-swj_newdap $_CHIPNAME cpu -expected-id $_CPUTAPID
+swd newdap $_CHIPNAME cpu -expected-id $_CPUTAPID
 dap create $_CHIPNAME.dap -chain-position $_CHIPNAME.cpu
 
 set _TARGETNAME $_CHIPNAME.cpu