stm32mp1: introduce shared resources support

stm32mp1: introduce shared resources support

STM32MP1 SoC includes peripheral interfaces that can be assigned to
the secure world, or that can be opened to the non-secure world.

This change introduces the basics of a driver that manages such
resources which assignation is done at run time. It currently offers
API functions that state whether a service exposed to non-secure
world has permission to access a targeted clock or reset controller.

Change-Id: Iff20028f41586bc501085488c03546ffe31046d8
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>