rockchip: Move to MULTI_CONSOLE_API

This patch changes all Rockchip platforms to use the new
MULTI_CONSOLE_API. The platform-specific plat_crash_console
implementations are removed so that the platform can use the ones from
the common platform code instead.

Also change the registers used in plat_crash_print_regs. The existing
use of x16 and x17 has always been illegal, since those registers are
reserved for use by the linker as a temporary scratch registers in
intra-procedure-call veneers and can never be expected to maintain their
values across a function call.

Change-Id: I8249424150be8d5543ed4af93b56756795a5288f
Signed-off-by: Julius Werner <jwerner@chromium.org>
diff --git a/plat/rockchip/rk3399/platform.mk b/plat/rockchip/rk3399/platform.mk
index f9d141d..9e369e4 100644
--- a/plat/rockchip/rk3399/platform.mk
+++ b/plat/rockchip/rk3399/platform.mk
@@ -64,6 +64,7 @@
 			${RK_PLAT_SOC}/drivers/dram/suspend.c
 
 ENABLE_PLAT_COMPAT	:=	0
+MULTI_CONSOLE_API	:=	1
 
 include lib/coreboot/coreboot.mk