arm: fix stack size
arm: fix stack size

According to GP Internal API, TA_STACK_SIZE corresponds to the stack
size used by the TA code itself and does not include stack space
possibly used by the Trusted Core Framework.
Hence, stack_size which is the size of the stack to use,
must be enlarged.

Without this patch, on FVP, xtest 1012, based on ta/sims, fails because
TA_STACK_SIZE is defined as 1024, which is too low.

Reviewed-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Signed-off-by: Pascal Brand <0b55292d2562685bad4ce52d64f802e8f1cd299e@st.com>

pascal-brand-st-dev/optee_os,matt2048/optee_os,cedric-chaumont-st-dev/optee_os,matt2048/optee_os,matt2048/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,cedric-chaumont-st-dev/optee_os,cedric-chaumont-st-dev/optee_os,matt2048/optee_os,cedric-chaumont-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os