B4860QDS and B4420QDS share same QDS board

* common board features have been added in b4qds.dts
* various board differences are in respective files of B4860 and B4420
Signed-off-by: NShaveta Leekha <shaveta@freescale.com>
Signed-off-by: NMinghuan Lian <Minghuan.Lian@freescale.com>
Signed-off-by: NAndy Fleming <afleming@freescale.com>
Signed-off-by: NPoonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: NRamneek Mehresh <ramneek.mehresh@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>