ARM: dts: imx6qdl-sr-som: add support for TI Wi-Fi

Add support for the TI Wi-Fi WL1837 device on SolidRun's revision
1.5 microsoms.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>