mtd: nand: xway: disable module support

BugLink: http://bugs.launchpad.net/bugs/1660993

commit 73529c87 upstream.

The xway_nand driver accesses the ltq_ebu_membase symbol which is not
exported. This also should not get exported and we should handle the
EBU interface in a better way later. This quick fix just deactivated
support for building as module.

Fixes: 99f2b107 ("mtd: lantiq: Add NAND support on Lantiq XWAY SoC.")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/mtd/nand/Kconfig

@@ -527,7 +527,7 @@ config MTD_NAND_FSMC
 	  Flexible Static Memory Controller (FSMC)
 
 config MTD_NAND_XWAY
-	tristate "Support for NAND on Lantiq XWAY SoC"
+	bool "Support for NAND on Lantiq XWAY SoC"
 	depends on LANTIQ && SOC_TYPE_XWAY
 	select MTD_NAND_PLATFORM
 	help