mmc: omap_hsmmc: Delete platform data GPIO CD and WP

The OMAP HSMMC driver has some elaborate and hairy handling for
passing GPIO card detect and write protect lines from a boardfile
into the driver: the machine defines a struct omap2_hsmmc_info
that is copied into struct omap_hsmmc_platform_data by
omap_hsmmc_pdata_init() in arch/arm/mach-omap2/hsmmc.c.

However the .gpio_cd and .gpio_wp fields are not copied from
omap2_hsmmc_info to omap_hsmmc_platform_data by
omap_hsmmc_pdata_init() so they remain unused. The only platform
defining omap2_hsmmc_info also define both to -1, unused.

It turn out there are no boardfiles passing any valid GPIO
lines into the OMAP HSMMC driver at all. And since we are not
going to add any more OMAP2 boardfiles, we can delete this
card detect and write protect handling altogether.

This seems to also fix a bug: the card detect callback
mmc_gpio_get_cd() in the slot GPIO core needs to be called
by drivers utilizing slot GPIO. It appears the the boardfile
quirks were not doing this right, so this would only get
called for boardfiles, i.e. since no boardfile was using it,
never.

Just assign mmc_gpio_get_cd() unconditionally to omap_hsmmc_ops
.get_cd() so card detects from the device tree works.
AFAICT card detect with GPIO lines assigned from
mmc_of_parse() are not working at the moment, but that is
no regression since it probably never worked.

Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>