feat(docs/nxp/layerscape): add ls1028a soc and board support

Update nxp-layerscape to add ls1028a SoC and ls1028ardb board
support.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: I9c7cc586f3718b488a6757994d65f6df69e7e165
1 file changed