ARM: dts: imx7d-sdb: fix ti,x-plate-ohms property name

Fix misspelled "ti,x-plate-ohms" property name of TI TSC2046
touchscreen controller.

Fixes: d09e6bea ("ARM: dts: imx7d-sdb: Add support for touchscreen")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>