ARM: dts: imx6qdl: phytec: Add support for optional PEB-EVAL-01 board

The PHYTEC PEV-EVAL-01 expansion board adds support for additional
gpio-triggered user-leds and gpio-key support.

Signed-off-by: Yunus Bas <y.bas@phytec.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>