lib: stm32wba: hci: Add flash_manager when building controller library

Flash manager is used to driver flash access coexistence between RF and
user accesses.

(cherry picked from commit 22925907a6faeb601fc9a0d8cbb65c4b26d38043)

Original-Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>
GitOrigin-RevId: 22925907a6faeb601fc9a0d8cbb65c4b26d38043
Change-Id: Iaf4ce0f1399e779009082f8f2a6a9dfecfa76809
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/hal_stm32/+/5136604
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Keith Short <keithshort@chromium.org>
Tested-by: Keith Short <keithshort@chromium.org>
Commit-Queue: Keith Short <keithshort@chromium.org>