dm: led: move default state support in led uclass

This patch save common LED property "default-state" value
in post bind of LED uclass.
The configuration for this default state is only performed when
led_default_state() is called;
It can be called in your board_init()
or it could added in init_sequence_r[] in future.

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