arm64: dts: imx8mp-var-som: Add WiFi and Bluetooth support

arm64: dts: imx8mp-var-som: Add WiFi and Bluetooth support

Add device tree nodes for the WiFi and Bluetooth module mounted on the
VAR-SOM-MX8MP. The module can be based on either the NXP IW612 or IW611
chipset, depending on the configuration chosen by the customer.

Regardless of the chipset used, WiFi communicates over SDIO and Bluetooth
over UART.

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