arm_adi_v5: put SWJ-DP back to JTAG mode at exit

arm_adi_v5: put SWJ-DP back to JTAG mode at exit

When SWD mode is used, current OpenOCD code left the SWJ-DP in
SWD mode at exit. Also, current code is unable to switch back the
SWJ-DP in JTAG at next run, thus a power cycle of both target and
interface is required in order to run OpenOCD in JTAG mode again.

Put the SWJ-DP back to JTAG mode before exit from OpenOCD.

Use switch_seq(SWD_TO_JTAG) instead of dap_to_jtag(), because the
latter is not implemented on some interfaces. This is aligned
with the use of switch_seq(JTAG_TO_SWD) in swd_connect().

Change-Id: I55d3faebe60d6402037ec39dd9700dc5f17c53b0
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4493
Tested-by: jenkins
Reviewed-by: Bohdan Tymkiv <bhdt@cypress.com>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>