drivers: introduce ST ETZPC driver ...

ETZPC stands for Extended TrustZone Protection Controller. It is a
resource conditional access device. It is mainly based on Arm TZPC.

ST ETZPC exposes memory mapped DECPROT cells to set access permissions
to SoC peripheral interfaces as I2C, SPI, DDR controllers, and some
of the SoC internal memories.

ST ETZPC exposes memory mapped TZMA cells to set access permissions
to some SoC internal memories.

Change-Id: I47ce20ffcfb55306dab923153b71e1bcbe2a5570
Co-developed-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>