feat(console): introduce EARLY_CONSOLE

This is a generic porting of what was done on ST platforms with flag
STM32MP_EARLY_CONSOLE. It creates the flag and the prototype for
plat_setup_early_console(). This function depends on platform
implementation. This function call is added at the beginning of each BL
image early setup function.
The patch also introduce an extra log macro: EARLY_ERROR. This can
replace ERROR macro in code that will only be executed before the
default console is enabled, and will do nothing when the EARLY_CONSOLE
is not enabled. This can then save some space in memory.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I77bf0a0c4289b4c7df94e4bfb783a938e05bf023
11 files changed