cpufreq: qcom-hw: use pre-defined core count for max cores

In order to support core boost where core counts is different than
the number of cores in the same frequency domain, use a predefined
value to determine max core count.

Change-Id: I076940b9b77f75ef1e5419bc3175635fb02a7549
Signed-off-by: David Dai <daidavid1@codeaurora.org>