hsmmc gpio updates

hsmmc gpio updates

Rework card detect GPIO handling in the twl4030 MMC glue:  drive
it *only* from the hsmmc_info passed; remove most of remaining
"we know we're always a twl4030 GPIO" logic.

Add write-protect switch detection support to that glue.  Stub
in a not-present WP GPIO into most boards.  (Beagle's is real.)

Teach the hsmmc driver how to use the card detect and writeprotect
methods, and move some data structure init earlier so that when IRQs
come in, more of the data used by their handlers is initialized.

Verified on Beagle (WP, card detect events) and Overo (boots, both
card and wlan are seen).  Beagle behaves fully, and is the model
to follow for the common case where the TWL4030 gpio-0 card detect
magic is used.

Most hsmmc boards need to list what GPIOs they use with MMC...

Note that supporting card detect and writeprotect GPIOs on a
second MMC slot, or using the MMC3 controller, requires some
interface updates that aren't part of this patch.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>