utils: Add BIT_32 and BIT_64 macros
utils: Add BIT_32 and BIT_64 macros

When applying some MISRA rules, lots of issues are raised with BIT macro
on AARCH32, and cast on uint32_t would be required (Rule 10.3).
The macros BIT_32 and BIT_64 are then created for 32bit and 64bit.
Then the BIT macro defaults on BIT_64 on AARCH64,
and on BIT_32 on AARCH32.

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

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