mtd: spi-nor: remove WARN_ONCE() message in spi_nor_write()

This patch removes the WARN_ONCE() test in spi_nor_write().
This macro triggers the display of a warning message almost every time we
use a UBI file-system because a write operation is performed at offset 64,
which is in the middle of the SPI NOR memory page. This is a valid
operation for ubifs.

Hence this warning is pretty annoying and useless so we just remove it.
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Suggested-by: Richard Weinberger <richard@nod.at>
Suggested-by: Andras Szemzo <szemzo.andras@gmail.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/spi-nor/spi-nor.c

@@ -1263,9 +1263,6 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 			page_offset = do_div(aux, nor->page_size);
 		}
-		WARN_ONCE(page_offset,
-			  "Writing at offset %zu into a NOR page. Writing partial pages may decrease reliability and increase wear of NOR flash.",
-			  page_offset);
 		/* the size of data remaining on the first page */
 		page_remain = min_t(size_t,
 				    nor->page_size - page_offset, len - i);