Add support for STM32L475xG SoC as a preliminary for
Discovery IOT board support.
stm32l476.dtsi file is now including stm32l475.dtsi
since STM32L476 SoC is a STM32L475 SoC with LCD support
Change-Id: I7567255e4172231cbf4899474617ecae0cd68d64
Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>