feat(st): add trace for early console

When the early console is configured with STM32MP_EARLY_CONSOLE,
display a message indicating it is enabled.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: Iafdfa5afef27eba823d707841853a8a46de0b42d
1 file changed