stm32mp1: use TZC400 macro to describe filters
stm32mp1: use TZC400 macro to describe filters

On STM32MP15, only filters 0 and 1 are used.
Use TZC_400_REGION_ATTR_FILTER_BIT() macro for those 2 filters 0 and 1
instead of U(3).

Change-Id: Ibc61823842ade680f59d5b66b8db59b6a30080e4
Signed-off-by: Yann Gautier <e753f6969c288905606e3c07464886d4f1fc1be0@st.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware