ARM: dts: imx27-phytec-phycore-som: Add WEIM node

This patch adds WEIM node for Phytec PCM-038 module.
Migrate existing on-module NOR-flash as children of WEIM CS0.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>