log: Add control over log formatting

It is useful to be able to control the output format of log records on the
console. As a starting point, add definitions for controlling which
elements of the log record are displayed. Use function and message as the
default, since these are the most useful fields.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/asm-generic/global_data.h

@@ -119,6 +119,7 @@ typedef struct global_data {
 	int log_drop_count;		/* Number of dropped log messages */
 	int default_log_level;		/* For devices with no filters */
 	struct list_head log_head;	/* List of struct log_device */
+	int log_fmt;			/* Mask containing log format info */
 #endif
 } gd_t;
 #endif