ARM: dts: imx27-phytec-phycore: Rename file to match functionality

PCM038 dts can be used as base for development kit board or any
custom PCB designs. Renames this file to match functionality.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>