boards: shields: frdm_kw41z: No reason to change chosen node

This nodelabel was changed while converting all shields to new nodelabel
scheme.
On this particular nodelabel, there was no change to be done, as it doesn't
refer to a node defined in the shield.
Revert this chagne.

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

boards/shields/frdm_kw41z/frdm_kw41z.overlay

@@ -6,7 +6,7 @@
 
 / {
 	chosen {
-		zephyr,bt-uart = &arduino_serial_frdm_kw41z;
+		zephyr,bt-uart = &arduino_serial;
 	};
 };