drivers/console: Reimplement MUTLI_CONSOLE_API framework in C

Now that we have switched to using the stack in MULTI_CONSOLE_API
framework functions and have factored all code involved in crash
reporting out into a separate file, there's really no reason to keep the
main framework code in assembly anymore. This patch rewrites it in C
which allows us to have a single implementation across aarch32/64 and
should be much easier to maintain going forward.

Change-Id: I6c85a01e89a79e8b233f3f8bee812f0dbd026221
Signed-off-by: Julius Werner <jwerner@chromium.org>
diff --git a/Makefile b/Makefile
index 63f283f..eed7c7a 100644
--- a/Makefile
+++ b/Makefile
@@ -214,7 +214,7 @@
 BL_COMMON_SOURCES	+=	common/bl_common.c			\
 				common/tf_log.c				\
 				common/${ARCH}/debug.S			\
-				drivers/console/${ARCH}/multi_console.S	\
+				drivers/console/multi_console.c		\
 				lib/${ARCH}/cache_helpers.S		\
 				lib/${ARCH}/misc_helpers.S		\
 				plat/common/plat_bl_common.c		\