ipq40xx: set #size-cells to 0 to fix warning

qcom-ipq4018-ex6100v2.dtb: Warning (reg_format): "reg" property in
	/led_spi/led_gpio@0 has invalid length (4 bytes)
qcom-ipq4018-ex6100v2.dtb: Warning (avoid_default_addr_size):
	Relying on default #size-cells value for /led_spi/led_gpio@0

Cc: Thomas Hebb <tommyhebb@gmail.com>
Cc: David Bauer <mail@david-bauer.net>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>