staging: erofs: fix `trace_erofs_readpage' position

`trace_erofs_readpage' was designed for .readpage() interface hook
in order to trace the detailed synchronized read rather than
the internal implementation `z_erofs_do_read_page' which both
.readpage() and .readpages() use.

It seems the tracepoint was placed to a wrong place by mistake and
it should be moved to the right place.

Fixes: 284db12c ("staging: erofs: add trace points for reading zipped data")
Reviewed-by: Chen Gong <gongchen4@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/unzip_vle.c

@@ -598,8 +598,6 @@ static int z_erofs_do_read_page(struct z_erofs_vle_frontend *fe,
 	unsigned int cur, end, spiltted, index;
 	int err = 0;
 
-	trace_erofs_readpage(page, false);
-
 	/* register locked file pages as online pages in pack */
 	z_erofs_onlinepage_init(page);
 
@@ -1288,6 +1286,8 @@ static int z_erofs_vle_normalaccess_readpage(struct file *file,
 	int err;
 	LIST_HEAD(pagepool);
 
+	trace_erofs_readpage(page, false);
+
 #if (EROFS_FS_ZIP_CACHE_LVL >= 2)
 	f.cachedzone_la = (erofs_off_t)page->index << PAGE_SHIFT;
 #endif