block: open accurate iostat account by default

hulk inclusion
category: bugfix
bugzilla: 187044, https://gitee.com/openeuler/kernel/issues/I5F2BY
CVE: NA

--------------------------------

Open accurate iostat account by default with setting the
"precise_iostat = 1" when initializing.
Signed-off-by: NZhang Wensheng <zhangwensheng5@huawei.com>
Reviewed-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

block/blk-core.c

@@ -56,7 +56,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
 
 DEFINE_IDA(blk_queue_ida);
 
-bool precise_iostat;
+bool precise_iostat = true;
 static int __init precise_iostat_setup(char *str)
 {
 	bool precise;