west.yml: hal_stm32: revert ble_fw blobs

Since the mkbox board ble f/w upgrade method based on binary
blobs that was proposed in #74255 has been turned down, all
the work done in hal_stm32 module to host blobs is now reverted.

Signed-off-by: Armando Visconti <armando.visconti@st.com>