OpenOCD can now be used to flash and debug nucleo_wba52cg.
However it required use of STMicroelectronics OpenOCD fork.

Add instructions on how to use it.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>

SW/JTAG signals description are useful when we don't need them.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>

At chip startup, jtag pins are configured by default to enable
debug.
This configuration adds consumption and when using PM profile,
we can save ~40uA by resetting this configuration and setting pins
to analog mode.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>

Provide jtag port pins description, so they can be used to be set in
analog mode when not required to save power (around 40uA saved in total).

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>

In some cases, PINCTRL_STATE_SLEEP may be required even when
CONFIG_PM_DEVICE is not defined.
One example is the possibility/need to put JTAG pins to analog when
CONIG_PM=y and CONFIG_DEBUG=n.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>