ARM: dts: n900: fix mmc1 card detect gpio polarity

Wrong polarity of card detect GPIO pin leads to the system not
booting from external mmc, if the back cover of N900 is closed.
When the cover is open the system boots fine.

This wasn't noticed before, because of a bug, which was fixed
by commit e63201f19 (mmc: omap_hsmmc: Delete platform data GPIO
CD and WP).

Kernels up to 4.19 ignored the card detect GPIO from DT.

Fixes: e63201f19438 ("mmc: omap_hsmmc: Delete platform data GPIO CD and WP")
Signed-off-by: Arthur Demchenkov <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

arch/arm/boot/dts/omap3-n900.dts

···
 	/* For debugging, it is often good idea to remove this GPIO.
 	   It means you can remove back cover (to reboot by removing
 	   battery) and still use the MMC card. */
-	cd-gpios = <&gpio6 0 GPIO_ACTIVE_HIGH>; /* 160 */
+	cd-gpios = <&gpio6 0 GPIO_ACTIVE_LOW>; /* 160 */
 };
 
 /* most boards use vaux3, only some old versions use vmmc2 instead */