ARM: dts: armada388-clearfog: move sdhci pinctrl node to microsom

Move the SDHCI pinctrl node to the microsom file - the microsom can have
optional eMMC support which uses these same pinctrl settings, so it is
sensible to have these here.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>