feat(stm32mp1): add early console in SP_min

Allow early console to be used at the beginning of SP_min, before
the clocks and UART have been reconfigured.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: I53d66938d42fcec830d9b81e5ef62b3790d0c3b3
1 file changed