feat(stm32mp1): add sign-compare warning

Add -Wsign-compare to TF_CFLAGS to check signedness comparison during
STM32MP1 platform compilation.

Change-Id: I4cada49622f44258d3e0da4560a566de9c7d54b3
Signed-off-by: Yann Gautier <yann.gautier@st.com>
1 file changed