bcache: Remove/fix some header dependencies

In the process of disentagling/libraryizing bset.c from the rest of the
bcache code.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/util.h

@@ -2,6 +2,7 @@
 #ifndef _BCACHE_UTIL_H
 #define _BCACHE_UTIL_H
 
+#include <linux/blkdev.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/llist.h>
@@ -391,6 +392,11 @@ struct time_stats {
 
 void bch_time_stats_update(struct time_stats *stats, uint64_t time);
 
+static inline unsigned local_clock_us(void)
+{
+	return local_clock() >> 10;
+}
+
 #define NSEC_PER_ns			1L
 #define NSEC_PER_us			NSEC_PER_USEC
 #define NSEC_PER_ms			NSEC_PER_MSEC