qemu: MULTI_CONSOLE_API=0 causes build error

Add crash_console_init declaration to console.h
Only enable MULTI_CONSOLE_API for AArch64

Fixes ARM-software/tf-issues#571

Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
diff --git a/include/drivers/console.h b/include/drivers/console.h
index f8ec83d..c8a43a2 100644
--- a/include/drivers/console.h
+++ b/include/drivers/console.h
@@ -66,6 +66,8 @@
 /* REMOVED on AArch64 -- use console_<driver>_register() instead! */
 int console_init(uintptr_t base_addr,
 		 unsigned int uart_clk, unsigned int baud_rate);
+int console_core_init(uintptr_t base_addr,
+		      unsigned int uart_clk, unsigned int baud_rate);
 void console_uninit(void);
 #endif