arm64: dts: imx8mp-venice-gw74xx: fix sai2 pin settings

The pad settings are missed, add them

Fixes: 7899eb6c ("arm64: dts: imx: Add i.MX8M Plus Gateworks gw7400 dts support")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>