ARM: dts: imx6qdl-sr-som: split out Broadcom Wi-Fi support

There are two variants of the imx6qdl som: one with Broadcom Wi-Fi and
another with Texas Instruments Wi-Fi.  The two Wi-Fi devices require
different DT bindings, so it's necessary to split out the Broadcom
specifics.

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>