ARM: dts: stm32: Don't probe led-red/led-blue at boot for stm32mp135f-dk-u-boot

ARM: dts: stm32: Don't probe led-red/led-blue at boot for stm32mp135f-dk-u-boot

led-red and button dedicated to fastboot share the same gpio GPIOA13.
led-blue and button dedicated to stm32prog share the same gpio GPIOA14.
Led driver is probed early so the corresponding gpio is taken and
configured in output which forbid fastboot and stm32prog button usage.

To avoid this, remove the "default-state" property from led-red and
led-blue led's node.

This will avoid to trigger the led driver probe() to configure the led
default state during startup.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>