BSEC services should return SMC error codes as other IDs (defined in
stm32mp1_smc.h) and not BSEC driver ones. So that non-secure caller
is able to treat them correctly.

In global SMC handler, unknown ID should also return a value from this
definition list, and not the generic one, which seems not well adapted
for our needs.

Two unsigned values initializations are also changed from 0 to 0U.

Change-Id: Ib6fd3866a748cefad1d13d48f7be38241621023e
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>