ARM: dts: imx6qdl-ts7970: Fix ngpio typo and count

Device-tree incorrectly used "ngpio" which caused the driver to
fallback to 32 ngpios.

This platform has 62 GPIO registers.

Fixes: 9ff8e9fc ("ARM: dts: TS-7970: add basic device tree")
Signed-off-by: Kris Bahnsen <kris@embeddedTS.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>