s5p sdhci: call pinmux for card's gpio pins before use them

The SD card detection depends on checking one pin state.
But the pin was configured after card was detected, which is wrong.

This commit fixes this, by moving call to pinmux before use the pin.

Tested-on: Odroid U3 and Odroid X2.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>