staging: erofs: remove incomplete cleancache

cleancache was not fully implemented in EROFS.
In addition, it's tend to remove the whole cleancache in
related attempt [1].

[1] https://lore.kernel.org/linux-fsdevel/20190527103207.13287-3-jgross@suse.com/Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190813023054.73126-2-gaoxiang25@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/data.c

@@ -201,12 +201,6 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio,
 		goto has_updated;
 	}
 
-	if (cleancache_get_page(page) == 0) {
-		err = 0;
-		SetPageUptodate(page);
-		goto has_updated;
-	}
-
 	/* note that for readpage case, bio also equals to NULL */
 	if (bio &&
 	    /* not continuous */

drivers/staging/erofs/internal.h

@@ -15,7 +15,6 @@
 #include <linux/pagemap.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.h>
-#include <linux/cleancache.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include "erofs_fs.h"