B4860 and B4420 are similar that share some commonalities

* common features have been added in b4si-pre.dtsi and b4si-post.dtsi
* differences are added in respective silicon files of B4860 and B4420

There are several things missing from the device trees of B4860 and B4420:

* DPAA related nodes (Qman, Bman, Fman, Rman)
* DSP related nodes/information
* serdes, sfp(security fuse processor), thermal,
  gpio, maple, cpri, quad timers nodes
Signed-off-by: NShaveta Leekha <shaveta@freescale.com>
Signed-off-by: NZhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: NLi Yang <leoli@freescale.com>
Signed-off-by: NTang Yuantian <Yuantian.Tang@freescale.com>
Signed-off-by: NVarun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: NMinghuan Lian <Minghuan.Lian@freescale.com>
Signed-off-by: NRamneek Mehresh <ramneek.mehresh@freescale.com>
Signed-off-by: NAndy Fleming <afleming@freescale.com>
Signed-off-by: NVakul Garg <vakul@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>