boards: shields: add mchp_rnbd451_bt#98043

JamesLiu-Microchip wants to merge 1 commit intozephyrproject-rtos:mainzephyrproject-rtos/zephyr:mainfrom

Zephyr4Microchip:shield_rnbd451_bt_upstreamZephyr4Microchip/zephyr:shield_rnbd451_bt_upstreamCopy head branch name to clipboard