canbus: rename zephyr,can-primary chosen property to zephyr,canbus

Rename the Zephyr chosen property for specifying the default CAN bus
controller from "zephyr,can-primary" to "zephyr,canbus".

The "zephyr,can-primary" property name was selected in antipation of
adding support for redundant CAN networks, which we have yet to
add. Meanwhile, the "primary" term causes confusion for non-redundant
CAN bus configurations (and the "can" term doesn't match the name of the
Zephyr CAN bus subsystem).

The CAN in Automation (CiA) 302-6, which deals with CANopen network
redundancy, uses the terms "default interface" and "redundant
interface". If/when we add support for redundant CAN networks, the
"zephyr,canbus" chosen property can be supplemented with a
"zephyr,canbus-redundant" chosen property.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
diff --git a/boards/arm/nucleo_l432kc/nucleo_l432kc.dts b/boards/arm/nucleo_l432kc/nucleo_l432kc.dts
index 4219402..71a6774 100644
--- a/boards/arm/nucleo_l432kc/nucleo_l432kc.dts
+++ b/boards/arm/nucleo_l432kc/nucleo_l432kc.dts
@@ -17,7 +17,7 @@
 		zephyr,shell-uart = &usart2;
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
-		zephyr,can-primary = &can1;
+		zephyr,canbus = &can1;
 	};
 
 	leds {