can: dts: Convert can-primary alias to zephyr,can-primary chosen prop

Convert CAN to use a chosen node property that is similar to how we
handle zephyr,entroy or zephyr,flash-controller as the means to select a
specific peripheral instance utilized by a subsystem.

Replace references of the form:

alias {
	can-primary = &can1;
};

with:

chosen {
	zephyr,can-primary = &can1;
};

Replace various macro/define references with either
DT_CHOSEN(zephyr_can_primary) or replace DT_ALIAS_CAN_PRIMARY_LABEL
with DT_CHOSEN_ZEPHYR_CAN_PRIMARY_LABEL.

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