Several SPI controller drivers have defined differently named properties for
the number of chip selects.  Now adding "num-cs" as a reference name for new
bindings.
Signed-off-by: NRoland Stigge <stigge@antcom.de>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>