Revert "dm: led: auto probe() LEDs with "default-state""

This reverts commit bc882f5d.
because this patch adds the probe of LED driver during the
binding phasis. It is not allowed in driver model because
the drivers (clock, pincontrol) needed by the LED driver can
be also probed before the binding of all the device and
it is a source of problems.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>