drivers: llcc_perfmon: support for dual memory controller added

llcc supports 2 memory controllers in backend on certain systems.
This patch adds support for dual memory controllers. Also fixed
filter related changes in LLCC. Cleaned up the code for better
code walk.

Change-Id: Ie054d9182b20ec0811f117c2289aa857f0384baf
Signed-off-by: Avinash Philip <avinashp@codeaurora.org>