ARM: pxa: Add GPIO descriptors for Palm27x

The Palm27x devices set up the MMC card detect and
write protect lines with a special helper function.
Augment this helper function to also accept an optional
GPIO descriptor table and pass and register this for
all the Palm27x devices in that family.

Cc: Daniel Mack <daniel@zonque.org>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Andrea Adami <andrea.adami@gmail.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>