target/adi_v5_swd: suppress reconnect in swd_multidrop_select()

target/adi_v5_swd: suppress reconnect in swd_multidrop_select()

swd_multidrop_select() uses its own retry loop.
If select fails, do_reconnect flag remains set on exit and causes
useless reconnect.

Clear do_reconnect flag in retry loop.

Change-Id: Ie06d6967d7f4a977774c8530bb8d4b3e5ab4f62c
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/7217
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Jonathan Bell <jonathan@raspberrypi.com>
Tested-by: jenkins