drm/msm/a6xx: Add support for an interconnect path

Try to get the interconnect path for the GPU and vote for the maximum
bandwidth to support all frequencies. This is needed for performance.
Later we will want to scale the bandwidth based on the frequency to
also optimize for power but that will require some device tree
infrastructure that does not yet exist.

v6: use icc_set_bw() instead of icc_set()
v5: Remove hardcoded interconnect name and just use the default
v4: Don't use a port string at all to skip the need for names in the DT
v3: Use macros and change port string per Georgi Djakov

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Acked-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>