ARM: dts: imx6ul-geam: Drop imx6ul-geam.dtsi

GEAM6UL SOM does have single module, it doesn't come with
any variants. Maintaining imx6ul-geam.dtsi make no sense
so move all devices from .dtsi into dts file and drop the same.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>