dm: pinctrl: introduce PINCONF_RECURSIVE option

In the Linux pinctrl binding, the pin configuration nodes don't need to
be direct children of the pin controller device (may be grandchildren for
example). This behavior is managed with the pinconfig u-class which
recursively bind all the sub-node of the pin controller.

But for some binding (when pin configuration is only children of pin
controller) that is not necessary. U-Boot can save memory and reduce
the number of pinconf instance when this feature is deactivated
(for arch stm32mp for example for SPL).

This patch allows to control this feature with a new option
CONFIG_PINCONF_RECURSIVE when it is possible for each individual
pin controller device.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Fixed CONFIG_IF_ENABLED() condition, added __maybe_unused:
Signed-off-by: Simon Glass <sjg@chromium.org>