powerpc/83xx: Update sdhci nodes per new bindings

As of commit 40461472

 ("Update FSL
esdhc binding"), we use "fsl,esdhc" compatible entry as a base
match. U-Boot will use the same compatible to fixup esdhc nodes.

This patch updates 83xx dts files so that they conform to the new
bindings.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>