arm64: dts: imx93-var-som-symphony: Add support for ft5x06 touch controller

arm64: dts: imx93-var-som-symphony: Add support for ft5x06 touch controller

The Symphony carrier board exposes a capacitive touch interface through an
FFC/FPC connector. This interface is wired to an FT5x06 touch controller
on the I2C bus when using Variscite’s 7-inch capacitive touch display.

This patch adds the FT5x06 device node to describe the actual hardware
connection and enables touch functionality on the Symphony board

Signed-off-by: Stefano Radaelli <stefano.r@variscite.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>