arm64: dts: mt7622: add flash related device nodes

add nodes for NOR flash, parallel Nand flash with error correction code
support.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Cc: RogerCC Lin <rogercc.lin@mediatek.com>
Cc: Guochun Mao <guochun.mao@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>