ARM: qcom: Re-organize platsmp to make it extensible

This makes it easy to add SMP support for new devices by keying
on a device node for the release sequence. We add the
enable-method property for the cpus property to specify that we
want to use the gcc-msm8660 release sequence (which is going to
look for the global clock controller device node to map some
Scorpion specific power and control registers). We also remove
the nr_cpus detection code as that is done generically in the DT
CPU detection code.

Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
[sboyd: Port to CPU_METHOD_OF_DECLARE]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>