esoc: Add support for autoboot

Some of the external SoC are flash based and can boot independently.
Extend esoc driver to support such auto boot esocs.

This patch also adds support for primary esoc. Primary esoc are
esoc that control secondary esoc such as modems. Primary esoc have
control over reset/poweroff of secondary esoc. Secondary esoc don't
have control over reset/poweroff of primary esoc. In general modems
are considered as secondary esoc while apps processor is considered
as primary esoc.

Change-Id: Id02417fcd122ac108cf75d3381ee7955f0f8f783
Signed-off-by: Arun KS <arunks@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rananta@codeaurora.org: resolved trivial conflicts]
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>