qapi: group BlockDeviceStats fields

Make the stat fields definition slightly more readable.
Also reorder total_time_ns stats read-write-flush as done elsewhere.
Cosmetic change only.
Signed-off-by: NAnton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190923121737.83281-2-anton.nefedov@virtuozzo.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

qapi/block-core.json

@@ -867,12 +867,12 @@
 # @flush_operations: The number of cache flush operations performed by the
 #                    device (since 0.15.0)
 #
-# @flush_total_time_ns: Total time spend on cache flushes in nano-seconds
-#                       (since 0.15.0).
+# @rd_total_time_ns: Total time spent on reads in nanoseconds (since 0.15.0).
 #
-# @wr_total_time_ns: Total time spend on writes in nano-seconds (since 0.15.0).
+# @wr_total_time_ns: Total time spent on writes in nanoseconds (since 0.15.0).
 #
-# @rd_total_time_ns: Total_time_spend on reads in nano-seconds (since 0.15.0).
+# @flush_total_time_ns: Total time spent on cache flushes in nanoseconds
+#                       (since 0.15.0).
 #
 # @wr_highest_offset: The offset after the greatest byte written to the
 #                     device.  The intended use of this information is for
@@ -925,14 +925,18 @@
 # Since: 0.14.0
 ##
 { 'struct': 'BlockDeviceStats',
-  'data': {'rd_bytes': 'int', 'wr_bytes': 'int', 'rd_operations': 'int',
-           'wr_operations': 'int', 'flush_operations': 'int',
-           'flush_total_time_ns': 'int', 'wr_total_time_ns': 'int',
-           'rd_total_time_ns': 'int', 'wr_highest_offset': 'int',
-           'rd_merged': 'int', 'wr_merged': 'int', '*idle_time_ns': 'int',
+  'data': {'rd_bytes': 'int', 'wr_bytes': 'int',
+           'rd_operations': 'int', 'wr_operations': 'int',
+           'flush_operations': 'int',
+           'rd_total_time_ns': 'int', 'wr_total_time_ns': 'int',
+           'flush_total_time_ns': 'int',
+           'wr_highest_offset': 'int',
+           'rd_merged': 'int', 'wr_merged': 'int',
+           '*idle_time_ns': 'int',
            'failed_rd_operations': 'int', 'failed_wr_operations': 'int',
-           'failed_flush_operations': 'int', 'invalid_rd_operations': 'int',
-           'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int',
+           'failed_flush_operations': 'int',
+           'invalid_rd_operations': 'int', 'invalid_wr_operations': 'int',
+           'invalid_flush_operations': 'int',
            'account_invalid': 'bool', 'account_failed': 'bool',
            'timed_stats': ['BlockDeviceTimedStats'],
            '*rd_latency_histogram': 'BlockLatencyHistogramInfo',