led_strip: apa102: Convert to new DT_<COMPAT>_<INSTANCE> defines
led_strip: apa102: Convert to new DT_<COMPAT>_<INSTANCE> defines

Convert apa102 led_strip driver to use new defines so we can remove
the dts_fixup.h code for it.

Also update the driver to set the slave spi address as specified by the
device tree.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

ldts/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,ldts/zephyr,galak/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,explora26/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,ldts/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,Vudentz/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,explora26/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr