msm: ipa: add support for equation based filter rules

An IPA filter rule can be specified in low-level equation
form. This commit adds support in IPA driver to correctly
process such a filter specification.

Change-Id: I64c08f9a27970a45798a59a4f9df6a1968e232c0
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>