ARM: dts: Leave sdio1 as disabled on bcm28155-ap

The sdio1 interface pins are routed to an unpopulated daughter card
connector on the bcm28155-ap board.  Thus there is no need to mark
this interface as enabled.

Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Matt Porter <mporter@linaro.org>