target/adi_v5_swd: introduce swd_queue_dp_read/write_inner()

target/adi_v5_swd: introduce swd_queue_dp_read/write_inner()

This is a preparatory change for swd multidrop, mostly refactoring.

Split swd_queue_dp_read/write() to inner and outer parts.
Use the inner parts in swd_queue_dp_bankselect(), swd_connect()
they do not need to check reconnect.
Use the outer parts exclusively in swd_dap_ops.

Rearrange the code to reduce forward declarations.

Change-Id: I47b7f0cb037e0032a267463f06ba02123ba96fe7
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/6139
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins