ARM: tegra: Use pwrseq-simple for the wifi in Nyan

The Nyan boards have a Marvell 88w8897 wifi card connected through SDIO
that needs the reset line to be asserted before mmc power up and deasserted
afterwards.

This patch also adds references to the power supplies of the card so that
the regulators are enabled when it's probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>