refactor(st): update test for closed chip

The function stm32mp_is_closed_device() is replaced with
stm32mp_check_closed_device(), which return an uint32_t, either
STM32MP_CHIP_SEC_OPEN or STM32MP_CHIP_SEC_CLOSED.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: Ie0790cdc36c4b6522083bc1f0e7c38e8061e6adf
6 files changed