lib: stm32wb: hci: fix gcc warnings

Patches lib WB HCI to avoid GCC warnings due to wrong buffer size.

(cherry picked from commit b8f135bac6347924c6719d645fd8082277616114)

Original-Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>
GitOrigin-RevId: b8f135bac6347924c6719d645fd8082277616114
Change-Id: If7500de597dd980c66c63995acee7af1c49faac1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/hal_stm32/+/4428766
Tested-by: CopyBot Service Account <copybot.service@gmail.com>
Tested-by: Keith Short <keithshort@chromium.org>
Reviewed-by: Keith Short <keithshort@chromium.org>
Commit-Queue: Keith Short <keithshort@chromium.org>