core_mmu.c: introduce add_va_space function
core_mmu.c: introduce add_va_space function

There can be more that one VA space. But old approach does not support
this because there can't be two VA spaces that begin at PA 0x0.

Signed-off-by: Volodymyr Babchuk <07adff7e050dc3230ac0b7d9c296bbb62f4ecc95@gmail.com>
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os