linux-imx

arm: kirkwood: add pinmux option for the SDIO interface on 88F6282

This commit adds a pinmux option, pmx_sdio, to enable the muxing of
the SDIO interface on the 88F6282 SoC from Marvell.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>