phy: qcom-qmp: Get dp_com I/O resource by index

The dp_com resource is always at index 1 according to the dts files in
the kernel. Get this resource by index so that we don't need to make
future additions to the DT binding use 'reg-names'.

Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Cc: Jeykumar Sankaran <jsanka@codeaurora.org>
Cc: Chandan Uddaraju <chandanu@codeaurora.org>
Cc: Vara Reddy <varar@codeaurora.org>
Cc: Tanmay Shah <tanmay@codeaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Manu Gautam <mgautam@codeaurora.org>
Cc: Sandeep Maheswaram <sanm@codeaurora.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Jonathan Marek <jonathan@marek.ca>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20200916231202.3637932-6-swboyd@chromium.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>