scsi: ufs: ufs-qcom: add basic interconnect support

The firmware on the Qualcomm platforms expects the interconnect votes to
be present. Let's add very basic support where the maximum throughput is
requested to match what's done in a few other drivers.

This will not break boot on systems where the interconnects and
interconnect-names properties are not specified in device tree for UFS
since the interconnect framework will silently return.

Signed-off-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>