feat(st-clock): stub fdt_get_rcc_secure_state

The function fdt_get_rcc_secure_state() is only used in BL32.
Put it under flag to avoid compilation errors.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: If57c65bef0b1a3f7349527720f94fde26edbb73c
1 file changed