mmc: s3cmci: Use the slot GPIO descriptor

Simplify things by making the S3CMCI driver just use
slot GPIO with descriptors instead of passing around the
global GPIO numbers that we want to get rid of.

Getting the names of the GPIO chips into the machine
descriptor tables was a bit of a challenge but I think
I have them right.

The platform data supports passing in inversion flags, but
no platform is using them, and it is highly unlikely
that we will add more, so drop them. The long term plan
is to let the inversion flags on the GPIO machine
descriptor do the job.

The lines are flagged as GPIO_ACTIVE_[LOW|HIGH] as that is
what they are, and since we can now rely on the descriptors
to have the right polarity, we set the
"override_active_level" to false in mmc_gpiod_request_cd()
and mmc_gpiod_request_ro().

Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Sergio Prado <sergio.prado@e-labworks.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>