include: pinctrl.h: Make PINCTRL_SKIP_SLEEP available with CONFIG_PM

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>