msm: pm-boot: Move initialization to postcore_initcall

msm_thermal module can bring a core online/offline for thermal conditions.
To be able to bring a core online, the msm-pm module should be able to set
the warmboot entry address when a core is being power collapsed, which is
set using the pm-boot module APIs. In scenarios, where msm_thermal tries to
bring a core online before pm-boot is initialized, the warmboot address for
the core isn't initialized causing the cpu to jump to execute from invalid
PC.

CRs-fixed: 622359
Change-Id: I692a4d8a5179fad2f4a81e6c8383a4bd56881235
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>