ARM: STi: remove sti_secondary_start from INIT section.

This patch removes sti_secondary_start from _INIT section, there are 2
reason for this removal.
 1. discarding such a small code does not save much, given the RAM
sizes.
 2. Having this code discarded, creates corruption issue when we boot
smp-kernel with nrcpus=1 or with single cpu node in DT.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: Olof Johansson <olof@lixom.net>