SDIO power work-around for B2

[John Watlington]

Chris, Mitch,
    I would like to wire up GPIO2, otherwise known as MSDT, to control
power to SDIO slot #2 (WLAN) after an ECO.   The ECO will be one
trace cut and one blue wire.

I don't know where in the plumbing this should happen (a quirk in the SD
stack, allowing it's reuse in B3 ?) but I believe OFW will have to  
change
the configuration of GPIO2/GPIO3 as well.

I'll provide units wired this way tmw. for testing.

Cheers,
wad