PM / devfreq: memlat: Add a core to memory frequency mapping table

Add a core to memory frequency mapping table, which establishes
a relationship between the core frequency and its corresponding
bandwidth vote.

The governor expects a "qcom,core-dev-table" table as part of a given
memlat hardware monitor's device tree node.

This table is read upon registration of the memlat governor. The table
is then used to determine the memory bandwidth vote corresponding to the
maximum of the core frequencies.

CRs-Fixed: 1054146
Change-Id: I9df118da1433125b02c937bf1799a0944b110fac
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
Signed-off-by: David Keitel <dkeitel@codeaurora.org>
Suggested-by: Saravana Kannan <skannan@codeaurora.org>