ARM: dts: Remove broken-voltage property from sdhci node for exynos4210-trats

The broken voltage property has been replaced with auto detection based
on voltages available on vmmc voltage regulator, so there is no use for
it now.

This patch removes the now unused property from Trats Device Tree
sources.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>