The STM32MP1 implementation of this function will call
plat_report_exception(). It displays more information about the panic
if DEBUG is enabled.
The LR register is also filled with R6 content, which hold the faulty
address. This allows debugger to reconstruct the backtrace.

Change-Id: I6710e8e2ab6658b05c5bbad2f3c545f07f355afb
Signed-off-by: Yann Gautier <yann.gautier@st.com>