ARM: dts: imx51-eukrea-mbimxsd51-baseboard: unbreak esdhc.

The following commit:
89d7e5c1

 mmc: sdhci-esdhc-imx: add runtime pm support
has the effect of also disabling the hardware card detect
in runtime pm.

We switch to GPIO based detection to avoid this issue.

This patch is based on:
ARM: dts: imx51-babbage: Fix esdhc setup

Signed-off-by: Denis Carikli <denis@eukrea.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>