fdt: added description comments to Device Tree update routines

	** this patch is picked from devel branch **
	** added description for 'mv_fdt_update_usb_vbus' **

Change-Id: I76871cee47cd7bc75f8f99a26a3b2d835515e56f
Signed-off-by: Shaker Daibes <shaker@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/17862
Reviewed-by: Omri Itach <omrii@marvell.com>
Tested-by: Omri Itach <omrii@marvell.com>
Signed-off-by: Bassel Saba <basselsa@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/19025
1 file changed