fdt: a38x: change card detection to DAT3 in DB-GP

	Since Marvell GP board revision ID v1.5, the SD card is detected using DAT3
	detection method.
	- add 'sd_detection_dat3 environment variable to indicate whether to support
	  dat3 or not, set default value for 'yes' only for DB-GP board
	- add property 'dat3-cd' to 'sdhci@X' node in DB-GP board
	  that depends on 'sd_detection_dat3' environment variable (value must be 'yes')

Change-Id: I3fb644ef0ce4d7d59db46eb35a8a8c4d29eba34b
Signed-off-by: Bassel Saba <basselsa@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/20405
Tested-by: Star_Automation <star@marvell.com>
Reviewed-by: Omri Itach <omrii@marvell.com>
2 files changed