mmc: pxamci: fix again read-only gpio detection polarity

mmc: pxamci: fix again read-only gpio detection polarity

The commit fixing the conversion of pxamci to slot-gpio API fixed the
inverted the logic of the read-only gpio. Unfortunately, the commit was
tested on a non-inverted gpio, and not on the inverted one. And the fix
did work partially, by luck.

This is the remaining missing part of the fix, trivial but still necessary.

Fixes: Fixes: 26d49fe71953 ("mmc: pxamci: fix read-only gpio detection polarity")
Reported-by: Andrea Adami <andrea.adami@gmail.com>
Tested-by: Andrea Adami <andrea.adami@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>