imx: Fix warning by building vf610twr_nand

imx: Fix warning by building vf610twr_nand

commit d6d07a9b... arm: vf610: add NAND support for vf610twr
generates the following warnings:

WARNING: no status info for 'vf610twr_nand'
WARNING: no maintainers for 'vf610twr_nand'WARNING: no status info for
'vf610twr_nand'

This is due to the fact that vf610twr_nand_defconfig has no Maintainer.
This patch proposed Alison as Maintainer and fix it.

Signed-off-by: Stefano Babic <sbabic@denx.de>
Acked-by: Alison Wang <b18965@freescale.com>
CC: Stefan Agner <stefan@agner.ch>