exynos: more debug and cleanup in do_sdhci_init()

Add more debug printfs in do_sdhci_init() for calls
that can potentially fail.

Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>
Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>