mgmt/osdp: Fix coverity identified off-by-one
mgmt/osdp: Fix coverity identified off-by-one

Fix a coverity identified, off-by-one, out-of-bound array access at
pd->cap[].

CID: 215379
Fixes: #33095
Signed-off-by: Siddharth Chandrasekaran <cf3591b207d7ad6b41008948dad8c0c751800981@embedjournal.com>

galak/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr