doc: migrate-guide: Add nxp frdm_mcxa166 migrate information.

NXP frdm_mcxa166 is renamed to frdm_mcxa346, add this
information to migration-guide-4.3.rst.

Signed-off-by: Zhaoxiang Jin <Zhaoxiang.Jin_1@nxp.com>

Author: ZhaoxiangJin

doc/releases/migration-guide-4.3.rst

@@ -29,6 +29,8 @@ Kernel
 Boards
 ******
 
+* NXP ``frdm_mcxa166`` is renamed to ``frdm_mcxa346``.
+
 Device Drivers and Devicetree
 *****************************