dts: quark_se: Refactor SoC dts.fixup into arch/x86/soc/intel_quark/<SOC>

Move common SoC dts.fixup defines into
arch/x86/soc/intel_quark/quark_se/dts.fixup so we remove duplication in
the boards and only have board specific defines in
boards/x86/<FOO>/dts.fixup.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>