Currently, on ARM platforms(ex. Juno) non-secure access to specific
peripheral regions, config registers which are inside and outside CSS
is done in the soc_css_security_setup(). This patch separates the CSS
security setup from the SOC security setup in the css_security_setup().

The CSS security setup involves programming of the internal NIC to
provide access to regions inside the CSS. This is needed only in
Juno, hence Juno implements it in its board files as css_init_nic400().

Change-Id: I95a1fb9f13f9b18fa8e915eb4ae2f15264f1b060