arm64: Move topology_init to postcore

Move topology_init to postcore initcall to retrieve
cpu frequency table early in boot from OPP.

Change-Id: I814a022f646878ee608f18ff740b5dc29c77a3c7
Signed-off-by: Shiju Mathew <shijum@codeaurora.org>
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>