ARM: SAMSUNG: Remove unnecessary exynos4_default_sdhci*()

Commit 17397a22("ARM: EXYNOS: Remove platform device initialization")
removes calling exynos4_default_sdhci*() functions; thus, these are
not necessary any more.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>