suspend/resume libertas_sdio device

[Hans-Jürgen Koch]

I'd like to suspend my 8686 when not needed, as it draws considerable
power. I noticed there's no .suspend/.resume in struct sdio_driver, so
how do I go about? Is there a recommended solution, or do I have to
hack up something myself?
I've got the power-down input of the 8686 connected to some GPIO, so
it'd be nice if I could define a function somewhere in my board
support that handles this.

Thanks,
Hans