spi: spi-qcom-qspi: Add interconnect support

Get the interconnect paths for QSPI device and vote according to the
current bus speed of the driver.

Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Akash Asthana <akashast@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/1592908737-7068-8-git-send-email-akashast@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>