ARM: dts: da850-lcdk: fix mmc card detect polarity

The polarity of the card detect pin is inverted.

Change it to reflect the right polarity for the board
which is ACTIVE_LOW.

Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>