ARM: dts: am335x-shc.dts: fix wrong cd pin level

cd pin on mmc1 is GPIO_ACTIVE_LOW not GPIO_ACTIVE_HIGH

Fixes: e63201f1

 ("mmc: omap_hsmmc: Delete platform data GPIO CD and WP")
Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>