feat(plat/st): add a function to configure console

To ease console configuration, a dedicated function is created:
stm32mp_uart_console_setup(). The code will also be common for the
different BLs.

Change-Id: Idf3cad756f125ca2313cf30b1311637a9df8f27f
Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index d45fbc7..d260644 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -53,6 +53,9 @@
 uintptr_t get_uart_address(uint32_t instance_nb);
 #endif
 
+/* Setup the UART console */
+int stm32mp_uart_console_setup(void);
+
 /*
  * Platform util functions for the GPIO driver
  * @bank: Target GPIO bank ID as per DT bindings