interconnect: qcom: Add support for PERF_MODE on RPMh targets

Add support for QCOM_ICC_TAG_PERF_MODE on RPMh architectures. When
QCOM_ICC_TAG_PERF_MODE is specified using icc_set_tag(), each node in
the requested path will use latency-optimized settings if supported by
the node. The improved latency comes at the cost of higher power.

Change-Id: I83c52e5677f8842b4c17987053d566971b84086f
Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>