dts: x86: Fix dts warnings when building up_squared

Fix the following dts warnings:

up_squared.dts_compiled: Warning (simple_bus_reg): /soc/gpio@0:
	simple-bus unit address format error, expected "d0c50000"
up_squared.dts_compiled: Warning (simple_bus_reg): /soc/i2c@91528000:
	simple-bus unit address format error, expected "9158000"

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