ARM: imx_v6_v7_defconfig: enable WEIM driver

enable the weim driver.
Since the NOR is connected to the WEIM for imx6q{dl}-sabreauto,
we also enable the MTD_PHYSMAP_OF module.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>