This function sets the address of the IO window used for
SDIO accesses onto the backplane of the chip.

It currently uses 3 separate masks despite the full mask being
defined in the code already. Remove the separate masks and clean up.
Signed-off-by: Ian Molton <ian@mnementh.co.uk>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>