wlcore: add device-tree support

When running with device-tree, we no longer have a board file
that can set up the platform data for wlcore.
Allow this data to be passed from DT.

Signed-off-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Tested-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Tested-by: Nikita Kiryanov <nikita@compulab.co.il>
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>