spi: Add support for Winbond W25Q128FW

The W25Q128FW spi part is programatically equivalent
to the other W25Q128 parts except it operates at 1.8V.
Just add a new entry with the appropriate ID.

Tested on a modified MinnowMax Board.

Change-Id: Id6a426418a7f785a9d959b02a9e3d2ffc421804f
Signed-off-by: Mohan D'Costa <mohan@ndr.co.jp>
Reviewed-on: http://review.coreboot.org/6971
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <gaumless@gmail.com>
Tested-by: build bot (Jenkins)

src/drivers/spi/winbond.c

@@ -110,6 +110,14 @@ static const struct winbond_spi_flash_params winbond_spi_flash_table[] = {
 		.nr_blocks		= 256,
 		.name			= "W25Q128",
 	},
+	{
+		.id			= 0x6018,
+		.l2_page_size		= 8,
+		.pages_per_sector	= 16,
+		.sectors_per_block	= 16,
+		.nr_blocks		= 256,
+		.name			= "W25Q128FW",
+	},
 };
 
 static int winbond_write(struct spi_flash *flash,