console: Split loglevel for fast and slow

For fast CBMEM console use minimum BIOS_DEBUG level.
For other consoles, Kconfig and/or nvram settings
apply.

Change-Id: Iff56a0a3182f258200cac80e013957d598cc2130
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/31370
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/include/console/console.h

@@ -62,6 +62,8 @@ void do_putchar(unsigned char byte);
 #define printk(LEVEL, fmt, args...) \
 	do { do_printk(LEVEL, fmt, ##args); } while (0)
 
+enum { CONSOLE_LOG_NONE = 0, CONSOLE_LOG_FAST, CONSOLE_LOG_ALL };
+
 #if IS_ENABLED(CONFIG_CONSOLE_OVERRIDE_LOGLEVEL)
 /*
  * This function should be implemented at mainboard level.